CompatHelper: bump compat for "Makie" to "0.15" for package test

[github-actions]

This pull request changes the compat entry for the Makie package from 0.13, 0.14 to 0.13, 0.14, 0.15 for package test.

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.

[coveralls]

Pull Request Test Coverage Report for Build 1035805819

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 23.529%

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Totals
Change from base Build 935594860:	0.0%
Covered Lines:	16
Relevant Lines:	68

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💛 - Coveralls

[codecov-commenter]

Codecov Report

Merging #25 (8010210) into main (9f25ba0) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #25   +/-   ##
=======================================
  Coverage   23.52%   23.52%           
=======================================
  Files           4        4           
  Lines          68       68           
=======================================
  Hits           16       16           
  Misses         52       52           

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