Benchmark CI fixes

[Erotemic]

Fix for issue introduced in #533

[codecov-commenter]

Codecov Report

Merging #534 (4e527b8) into main (a900e46) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #534   +/-   ##
=======================================
  Coverage   91.76%   91.76%           
=======================================
  Files           6        6           
  Lines        1821     1821           
=======================================
  Hits         1671     1671           
  Misses        150      150           

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[Erotemic]

@hugovk looks like I forgot to add a default case to --disable. I fixed that and added the lines to test the benchmarks in the PR if the file itself is changed (which is really cool, I didn't know you could conditionally run workflows based on if a specific file is part of the commit).

[hugovk]

Thank you!