CompatHelper: bump compat for EulerLagrange to 0.4, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the EulerLagrange package from 0.3 to 0.3, 0.4.
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 33.33%. Comparing base (0946a09) to head (29e3675).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #74   +/-   ##
=======================================
  Coverage   33.33%   33.33%           
=======================================
  Files          30       30           
  Lines        2016     2016           
=======================================
  Hits          672      672           
  Misses       1344     1344           

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