CompatHelper: add new compat entry for NCDatasets at version 0.12, (keep existing compat)

[github-actions]

This pull request sets the compat entry for the NCDatasets package to 0.12.
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.
Note: Consider registering a new release of your package immediately after merging this PR, as downstream packages may depend on this for tests to pass.

[codecov-commenter]

Codecov Report

Merging #86 (a3b6c57) into main (9fc5fc1) will increase coverage by 1.15%.
The diff coverage is n/a.

❗ Current head a3b6c57 differs from pull request most recent head d9e8e20. Consider uploading reports for the commit d9e8e20 to get more accurate results

@@            Coverage Diff             @@
##             main      #86      +/-   ##
==========================================
+ Coverage   95.10%   96.25%   +1.15%     
==========================================
  Files          15       15              
  Lines         347      347              
==========================================
+ Hits          330      334       +4     
+ Misses         17       13       -4     

see 1 file with indirect coverage changes