CompatHelper: bump compat for ApproxFun to 0.13, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the ApproxFun package from 0.12 to 0.12, 0.13.
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-commenter]

Codecov Report

Merging #28 (966344d) into master (c1f8289) will increase coverage by 1.13%.
Report is 7 commits behind head on master.
The diff coverage is n/a.

❗ Current head 966344d differs from pull request most recent head 4371505. Consider uploading reports for the commit 4371505 to get more accurate results

@@            Coverage Diff             @@
##           master      #28      +/-   ##
==========================================
+ Coverage   75.53%   76.66%   +1.13%     
==========================================
  Files          32       29       -3     
  Lines        3172     1363    -1809     
==========================================
- Hits         2396     1045    -1351     
+ Misses        776      318     -458     

see 60 files with indirect coverage changes

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