Fix AttributeError in petab_import_pysb with petab==0.2.0

[dweindl]

Closes #2078

[codecov]

Codecov Report

Merging #2079 (369c224) into develop (1ee58c4) will increase coverage by 1.16%.
The diff coverage is 93.42%.

❗ Current head 369c224 differs from pull request most recent head e226d5a. Consider uploading reports for the commit e226d5a to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2079      +/-   ##
===========================================
+ Coverage    53.73%   54.90%   +1.16%     
===========================================
  Files           29       30       +1     
  Lines         4548     4617      +69     
===========================================
+ Hits          2444     2535      +91     
+ Misses        2104     2082      -22     

Flag	Coverage Δ
petab	54.90% <93.42%> (+1.16%)	⬆️
sbmlsuite	?

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

Impacted Files	Coverage Δ
python/sdist/amici/petab_import_pysb.py	9.25% <0.00%> (ø)
python/sdist/amici/petab_objective.py	93.77% <93.47%> (+0.34%)	⬆️
python/sdist/amici/petab_import.py	69.41% <100.00%> (+3.92%)	⬆️
python/tests/test_petab_objective.py	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

[FFroehlich]

tests in #1800 would have caught this, right?

[dweindl]

tests in #1800 would have caught this, right?

That specific part is removed in #1800

The test cases to catch this have silently disappeared with the changes in the PEtab test suite. The hacky pysb test cases there have been replaced by the petab v2 cases, but those are only used in #1800. Didn't realize that either until earlier today.

EDIT: Would rather try to get #1800 done soon, instead of getting the old tests running again.