chore(ci): apply a few easy hardenings suggested by zizmore

[CommanderStorm]

This PR makes a few of our actions a bit more resistant against supply chain security

In terms of actual risk, the biggest issue (how we bump versions) remains

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.37%. Comparing base (d393242) to head (50b3dc1).
⚠️ Report is 10 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1316   +/-   ##
=======================================
  Coverage   95.37%   95.37%           
=======================================
  Files         114      114           
  Lines        7398     7398           
  Branches     2327     2327           
=======================================
  Hits         7056     7056           
  Misses        342      342           

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