CompatHelper: bump compat for Optimisers to 0.3, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the Optimisers package from 0.2 to 0.2, 0.3.
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

Patch coverage has no change and project coverage change: -1.12% ⚠️

Comparison is base (6125b5e) 81.11% compared to head (7a8e4fa) 80.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #18      +/-   ##
==========================================
- Coverage   81.11%   80.00%   -1.12%     
==========================================
  Files          14       11       -3     
  Lines         503      460      -43     
==========================================
- Hits          408      368      -40     
+ Misses         95       92       -3     

see 12 files with indirect coverage changes

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