debian: Avoid building examples

before:

dpkg -c /var/cache/pbuilder/result/bookworm-amd64/golang-github-mmatczuk-anyflag-dev_0.0~git20231026.5f42d2f-1_all.deb 
drwxr-xr-x root/root         0 2023-11-14 07:13 ./
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/bin/
-rwxr-xr-x root/root   4171096 2023-11-14 07:13 ./usr/bin/enum
-rwxr-xr-x root/root   4171240 2023-11-14 07:13 ./usr/bin/enum-stringer
-rwxr-xr-x root/root   4386896 2023-11-14 07:13 ./usr/bin/json-map
-rwxr-xr-x root/root   4238608 2023-11-14 07:13 ./usr/bin/redact
-rwxr-xr-x root/root   4238224 2023-11-14 07:13 ./usr/bin/url
-rwxr-xr-x root/root   4158072 2023-11-14 07:13 ./usr/bin/validation
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/doc/
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/doc/golang-github-mmatczuk-anyflag-dev/
-rw-r--r-- root/root       181 2023-11-14 07:13 ./usr/share/doc/golang-github-mmatczuk-anyflag-dev/changelog.Debian.gz
-rw-r--r-- root/root      1070 2023-11-14 07:13 ./usr/share/doc/golang-github-mmatczuk-anyflag-dev/copyright
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/github.com/
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/
-rw-r--r-- root/root       886 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/enum.go
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/enum/
-rw-r--r-- root/root       957 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/enum/cmd.go
-rw-r--r-- root/root       208 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/enum/cmd_test.go
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/enum-stringer/
-rw-r--r-- root/root       837 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/enum-stringer/cmd.go
-rw-r--r-- root/root       208 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/enum-stringer/cmd_test.go
-rw-r--r-- root/root       684 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/enum-stringer/pill_string.go
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/json-map/
-rw-r--r-- root/root       637 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/json-map/cmd.go
-rw-r--r-- root/root       153 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/json-map/cmd_test.go
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/redact/
-rw-r--r-- root/root       807 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/redact/cmd.go
-rw-r--r-- root/root       314 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/redact/cmd_test.go
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/url/
-rw-r--r-- root/root       658 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/url/cmd.go
-rw-r--r-- root/root       278 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/url/cmd_test.go
drwxr-xr-x root/root         0 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/validation/
-rw-r--r-- root/root       816 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/validation/cmd.go
-rw-r--r-- root/root       260 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/examples/validation/cmd_test.go
-rw-r--r-- root/root       184 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/go.mod
-rw-r--r-- root/root       896 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/go.sum
-rw-r--r-- root/root      2505 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/slice.go
-rw-r--r-- root/root      4231 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/slice_test.go
-rw-r--r-- root/root      1389 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/value.go
-rw-r--r-- root/root      1532 2023-11-14 07:13 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/value_test.go

after:

$ dpkg -c /var/cache/pbuilder/result/bookworm-amd64/golang-github-mmatczuk-anyflag-dev_0.0~git20231026.5f42d2f-2_all.deb 
drwxr-xr-x root/root         0 2024-01-03 11:25 ./
drwxr-xr-x root/root         0 2024-01-03 11:25 ./usr/
drwxr-xr-x root/root         0 2024-01-03 11:25 ./usr/share/
drwxr-xr-x root/root         0 2024-01-03 11:25 ./usr/share/doc/
drwxr-xr-x root/root         0 2024-01-03 11:25 ./usr/share/doc/golang-github-mmatczuk-anyflag-dev/
-rw-r--r-- root/root       233 2024-01-03 11:25 ./usr/share/doc/golang-github-mmatczuk-anyflag-dev/changelog.Debian.gz
-rw-r--r-- root/root      1070 2023-11-14 07:23 ./usr/share/doc/golang-github-mmatczuk-anyflag-dev/copyright
drwxr-xr-x root/root         0 2024-01-03 11:25 ./usr/share/gocode/
drwxr-xr-x root/root         0 2024-01-03 11:25 ./usr/share/gocode/src/
drwxr-xr-x root/root         0 2024-01-03 11:25 ./usr/share/gocode/src/github.com/
drwxr-xr-x root/root         0 2024-01-03 11:25 ./usr/share/gocode/src/github.com/mmatczuk/
drwxr-xr-x root/root         0 2024-01-03 11:25 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/
-rw-r--r-- root/root       886 2024-01-03 11:25 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/enum.go
-rw-r--r-- root/root       184 2024-01-03 11:25 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/go.mod
-rw-r--r-- root/root       896 2024-01-03 11:25 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/go.sum
-rw-r--r-- root/root      2505 2024-01-03 11:25 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/slice.go
-rw-r--r-- root/root      4231 2024-01-03 11:25 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/slice_test.go
-rw-r--r-- root/root      1389 2024-01-03 11:25 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/value.go
-rw-r--r-- root/root      1532 2024-01-03 11:25 ./usr/share/gocode/src/github.com/mmatczuk/anyflag/value_test.go