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

[github-actions]

This pull request changes the compat entry for the MetaGraphsNext 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 94.00%. Comparing base (9e82e80) to head (73cf2d6).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #61   +/-   ##
=======================================
  Coverage   94.00%   94.00%           
=======================================
  Files           2        2           
  Lines         100      100           
=======================================
  Hits           94       94           
  Misses          6        6           

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