Put output dir to tmp_path

[pnuu]

The TestSaveDatasets.test_pop_unknown_args is creating a Hungarian directory and not removing it. This PR fixes it by using tmp_path fixture.

• Closes Test directory not removed after tests #155
• Tests modified
• Tests passed
• Passes flake8 trollflow2

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.96%. Comparing base (98355d9) to head (f834043).
Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #224   +/-   ##
=======================================
  Coverage   95.96%   95.96%           
=======================================
  Files          14       14           
  Lines        3268     3272    +4     
=======================================
+ Hits         3136     3140    +4     
  Misses        132      132           

Flag	Coverage Δ
unittests	95.96% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[gerritholl]

I didn't think with all the mocking anything would be created at all, but looks good to me.