py: tests: make tests run under PyPy

[zougloub]

Closes #157

[codecov-commenter]

Codecov Report

Merging #158 (ad1c62f) into main (b348312) will increase coverage by 0.32%.
The diff coverage is n/a.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #158      +/-   ##
==========================================
+ Coverage   87.40%   87.73%   +0.32%     
==========================================
  Files          24       24              
  Lines        1604     1622      +18     
  Branches       74       79       +5     
==========================================
+ Hits         1402     1423      +21     
- Misses        184      185       +1     
+ Partials       18       14       -4     

[MatthieuDartiailh]

I am confused as to why PyPy stopped using the qualname. But given this does not affect the correctness of the code I am fine with relaxing the tests. Thanks for the PR