Use log file in tmp_path instead of 'somefile'

[pnuu]

Simple fix for the logging tests which were writing a somefile on the filesystem. Now we use tmp_path fixture instead and check that the new log file exists when it should.

• Closes #xxxx
• Tests added
• Fully documented
• Add your name to AUTHORS.md if not there already

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.15%. Comparing base (7c50b7b) to head (10c99e2).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #193      +/-   ##
==========================================
+ Coverage   91.08%   91.15%   +0.07%     
==========================================
  Files          26       26              
  Lines        5370     5426      +56     
==========================================
+ Hits         4891     4946      +55     
- Misses        479      480       +1     

Flag	Coverage Δ
unittests	91.15% <100.00%> (+0.07%)	⬆️

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[mraspaud]

LGTM!