tests: add integration test for pull_request_target

[zmiklank]

Would be good to have some simple setup for different targets in our integration tests.
I am setting this to a draft for now, as we need to make sure the test is written safely before we merge it.

[zmiklank]

If we use pull_request_target we need to checkout specifically to the PR HEAD SHA.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.28%. Comparing base (b1c8c43) to head (37ec6bc).
Report is 13 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #139   +/-   ##
=======================================
  Coverage   99.28%   99.28%           
=======================================
  Files           8        8           
  Lines         563      563           
  Branches       61       61           
=======================================
  Hits          559      559           
  Misses          4        4           

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[zmiklank]

[test]