allow forks to be linted

[tobikris]

Found here: actions/checkout#455 (comment)

[codecov-commenter]

Codecov Report

Merging #317 (eb1a011) into master (63d572c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #317   +/-   ##
=======================================
  Coverage   53.36%   53.36%           
=======================================
  Files         145      145           
  Lines        7081     7081           
=======================================
  Hits         3779     3779           
  Misses       3119     3119           
  Partials      183      183           

Flag	Coverage Δ
unittests	53.36% <ø> (ø)

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