CompatHelper: bump compat for IntervalSets to 0.6, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the IntervalSets package from 0.5 to 0.5, 0.6.
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

Merging #9 (22fe390) into main (6d4a18c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main       #9   +/-   ##
=======================================
  Coverage   98.77%   98.77%           
=======================================
  Files           6        6           
  Lines         245      245           
=======================================
  Hits          242      242           
  Misses          3        3           

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