ci: remove broken readmechanged workflow

[TomJGooding]

Remove the broken workflow to send notifications on README changes.

This workflow stopped working a long time ago and presumably is no longer needed.

Type of changes

• Bug fix
• New feature
• Documentation / docstrings
• Tests
• Other

AI?

• AI was used to generate this PR

AI generated PRs may be accepted, but only if @willmcgugan has responded on an issue or discussion.

Checklist

• I've run the latest black with default args on new code.
• I've updated CHANGELOG.md and CONTRIBUTORS.md where appropriate (see note about typos above).
• I've added tests for new code.
• I accept that @willmcgugan may be pedantic in the code review.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.87%. Comparing base (2e5a5da) to head (97fc5fe).
⚠️ Report is 10 commits behind head on master.
❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3973   +/-   ##
=======================================
  Coverage   97.87%   97.87%           
=======================================
  Files          96       96           
  Lines        8363     8366    +3     
=======================================
+ Hits         8185     8188    +3     
  Misses        178      178           

Flag	Coverage Δ
unittests	97.87% <ø> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.