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

[github-actions]

This pull request changes the compat entry for the DiffEqCallbacks package from 2, 3 to 2, 3, 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 54.47%. Comparing base (0b7924d) to head (fa4a94b).
Report is 4 commits behind head on main.

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HEAD has 3 uploads less than BASE

Flag	BASE (0b7924d)	HEAD (fa4a94b)
	4	1

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #107       +/-   ##
===========================================
- Coverage   89.08%   54.47%   -34.62%     
===========================================
  Files          20       20               
  Lines        1484     1454       -30     
===========================================
- Hits         1322      792      -530     
- Misses        162      662      +500     

Flag	Coverage Δ
	54.47% <ø> (?)

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