CompatHelper: bump compat for BAT to 2, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the BAT package from 3 to 3, 2.
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

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The diff coverage is n/a.

@@           Coverage Diff           @@
##             main       #1   +/-   ##
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  Coverage        ?   79.58%           
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  Files           ?        3           
  Lines           ?      240           
  Branches        ?        0           
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  Hits            ?      191           
  Misses          ?       49           
  Partials        ?        0           

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[oschulz]

Leaving this open to keep CompatHelper quiet, but PartitionedParallelSampling won't support BAT v2.