Add option to not remove temporary directories

[dweindl]

Convenient for debugging purposes in order to keep directories without rewriting a test using a tempdir.

[codecov]

Codecov Report

Merging #2221 (2dca397) into develop (52b1af6) will decrease coverage by 0.01%.
The diff coverage is 71.42%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2221      +/-   ##
===========================================
- Coverage    76.50%   76.50%   -0.01%     
===========================================
  Files           91       91              
  Lines        15034    15041       +7     
===========================================
+ Hits         11502    11507       +5     
- Misses        3532     3534       +2     

Flag	Coverage Δ
cpp	73.08% <ø> (ø)
cpp_python	37.03% <ø> (ø)
petab	53.79% <71.42%> (+0.02%)	⬆️
python	77.12% <71.42%> (-0.01%)	⬇️
sbmlsuite	?

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

Files	Coverage Δ
python/sdist/amici/testing.py	64.70% <71.42%> (+4.70%)	⬆️