Use tmp_path in test_mainfunction

[larsevj]

Avoids creating a specific file in the /tmp directory, which would make tests fail if run with different users on same machine.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3df859c) 86.26% compared to head (a2db279) 86.26%.

❗ Current head a2db279 differs from pull request most recent head 52d4e17. Consider uploading reports for the commit 52d4e17 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #667   +/-   ##
=======================================
  Coverage   86.26%   86.26%           
=======================================
  Files          50       50           
  Lines        6990     6990           
=======================================
  Hits         6030     6030           
  Misses        960      960           

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