chore: pin GitHub Actions workflows to full commit SHAs

[irfanuddinahmad]

Pins all uses: action refs to their full commit SHA with the version tag preserved as a comment. Part of org-wide SHA-pinning migration: openedx/.github#165

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.40%. Comparing base (9340b9c) to head (ee24e03).
⚠️ Report is 2 commits behind head on release-23.x.

Additional details and impacted files

@@              Coverage Diff              @@
##           release-23.x    #4301   +/-   ##
=============================================
  Coverage         94.40%   94.40%           
=============================================
  Files               242      242           
  Lines              4309     4309           
  Branches            981     1020   +39     
=============================================
  Hits               4068     4068           
+ Misses              237      233    -4     
- Partials              4        8    +4     

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