CompatHelper: bump compat for SubsurfaceCore to 0.8, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the SubsurfaceCore package from 0.7 to 0.7, 0.8.
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 46.48%. Comparing base (524600a) to head (f6ab1ca).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #29   +/-   ##
=======================================
  Coverage   46.48%   46.48%           
=======================================
  Files          25       25           
  Lines        1095     1095           
=======================================
  Hits          509      509           
  Misses        586      586           

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