chore: Add action to validate PR titles

[mister-ben]

Description

Adds a GitHub action to validate that PR titles follow conventional commit, to make sure we don't merge a PR that wouldn't show up in the change log.

Specific Changes proposed

Adds a simple action to validate the title with a regex. There are GitHub marketplace actions which will do this, but they have a lot of dependencies and configuration options we don't need for now.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.71%. Comparing base (6eb0230) to head (1deaa81).
Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8614   +/-   ##
=======================================
  Coverage   82.71%   82.71%           
=======================================
  Files         113      113           
  Lines        7636     7636           
  Branches     1835     1835           
=======================================
  Hits         6316     6316           
  Misses       1320     1320           

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[amtins]

LGTM, I have a question, though: why not introduce a tool like commitlint?

[mister-ben]

LGTM, I have a question, though: why not introduce a tool like commitlint?

That would enforce the format on each individual commit message, which isn't too important as we squash and merge, and wouldn't stop the PR title from being changed to something that doesn't fit.