CompatHelper: bump compat for ParametricOptInterface to 0.15, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the ParametricOptInterface package from 0.14.1 to 0.14.1, 0.15.
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 90.20%. Comparing base (0c84ac7) to head (56d497e).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #343   +/-   ##
=======================================
  Coverage   90.20%   90.20%           
=======================================
  Files          16       16           
  Lines        2164     2164           
=======================================
  Hits         1952     1952           
  Misses        212      212           

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