Release runs only on version tags created on main

[ciroque]

Proposed changes

Prior to this it was possible to run the release process on any branch. These changes ensure that only tags created on main will trigger the release process.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• [X] I have read the CONTRIBUTING document
• [X] If applicable, I have added tests that prove my fix is effective or that my feature works
• [X] If applicable, I have checked that any relevant tests pass after adding my changes
• [X] I have updated any relevant documentation (README.md and CHANGELOG.md)

[ciroque]

Stale