Rebase our fork of conda-pack with latest from upstream

This is to see if the recent conda-pack works with the recent conda and libmamba.

I did the following:

git clone git@gitlab.wikimedia.org:repos/data-engineering/conda-pack.git
cd conda-pack
git remote add upstream git@github.com:conda/conda-pack.git
git checkout -b get-conda-pack-synced-with-upstream
git fetch upstream
git rebase upstream/main
git push origin