add --nbmake-find-import-errors

[alex-treebeard]

Runs cells ignoring timeouts and errors other than ModuleNotFoundErrors

https://github.com/treebeardtech/nbmake/issues/86

[codecov[bot]]

Codecov Report

Merging #87 (a7ac96c) into main (966edac) will decrease coverage by 0.55%. The diff coverage is 89.65%.

@@            Coverage Diff             @@
##             main      #87      +/-   ##
==========================================
- Coverage   92.46%   91.90%   -0.56%     
==========================================
  Files           4        4              
  Lines         146      173      +27     
==========================================
+ Hits          135      159      +24     
- Misses         11       14       +3     

Impacted Files	Coverage Δ
src/nbmake/pytest_items.py	88.46% <ø> (ø)
src/nbmake/pytest_plugin.py	91.66% <83.33%> (-3.08%)	:arrow_down:
src/nbmake/nb_run.py	93.10% <91.30%> (-0.75%)	:arrow_down: