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

[github-actions]

This pull request changes the compat entry for the DiffEqCallbacks package from 2.25 to 2.25, 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 96.34%. Comparing base (0c2c367) to head (88884ac).
Report is 135 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2091   +/-   ##
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  Coverage   96.34%   96.34%           
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  Files         470      470           
  Lines       37512    37512           
=======================================
  Hits        36140    36140           
  Misses       1372     1372           

Flag	Coverage Δ
unittests	96.34% <ø> (ø)

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[sloede]

The tests pass, but then again, they seem to be using DiffEqCallbacks v2.37.0. Should we merge anyways?

[ranocha]

No. We should wait until dependencies have been updated to test the new version.

[ranocha]

It's still using the old version, see https://github.com/trixi-framework/Trixi.jl/actions/runs/11139766106/job/30957092767?pr=2091#step:7:123