deploy-promote: make version matching regex less brittle
While at the same time still trying to be specific enough to capture the MW version correctly.
Bug: T336269
How to register an account on GitLab. To prevent spam, new accounts are locked until approved by an admin or the approver bot. You can also file an unlock request to expedite access.
Support: mw:GitLab, how to host a project on GitLab, #wikimedia-gitlab on libera.chat, #GitLab on Phabricator.
While at the same time still trying to be specific enough to capture the MW version correctly.
Bug: T336269