Revert pypy pin and skip stalled tests

[blnicho]

Fixes # .

Summary/Motivation:

The PyPy job is consistently getting stuck. In #3899 we added a temporary pin to the PyPy version we use for testing to work around issues in the 7.3.21 release. PyPy 7.3.22 is out now so this PR reverts the pin to see if that resolves the new issue we're seeing.

Changes proposed in this PR:

• Remove PyPy pin to make sure we're testing the latest version

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.02%. Comparing base (b953cf9) to head (0a3b616).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4002      +/-   ##
==========================================
- Coverage   90.13%   90.02%   -0.12%     
==========================================
  Files         917      917              
  Lines      109101   109101              
==========================================
- Hits        98343    98221     -122     
- Misses      10758    10880     +122     

Flag	Coverage Δ
builders	29.09% <100.00%> (+0.01%)	⬆️
default	86.13% <100.00%> (?)
expensive	35.07% <100.00%> (?)
linux	87.66% <100.00%> (-1.98%)	⬇️
linux_other	87.66% <100.00%> (+<0.01%)	⬆️
oldsolvers	27.91% <100.00%> (-0.12%)	⬇️
osx	83.11% <100.00%> (ø)
win	85.42% <100.00%> (ø)

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