CompatHelper: bump compat for RecursiveArrayTools to 4, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the RecursiveArrayTools package from 3.42 to 3.42, 4.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.48%. Comparing base (b39a88d) to head (bec80cc).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #76   +/-   ##
=======================================
  Coverage   98.48%   98.48%           
=======================================
  Files          24       24           
  Lines        1847     1847           
=======================================
  Hits         1819     1819           
  Misses         28       28           

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[JoshuaLampert]

Should be done in #74.