MAINT: pin pytest<7 in pypy3 CI

[lesteve]

similar to #1261 but for pypy

Also tweak the comments, I don't think this causes freezes but only test errors because there are additional PytestRemovedIn8Warning (but maybe I missed something ...)

[codecov]

Codecov Report

Merging #1262 (31e7f53) into master (732923a) will increase coverage by 0.15%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1262      +/-   ##
==========================================
+ Coverage   88.21%   88.37%   +0.15%     
==========================================
  Files          47       47              
  Lines        7045     7045              
==========================================
+ Hits         6215     6226      +11     
+ Misses        830      819      -11     

Impacted Files	Coverage Δ
joblib/hashing.py	91.22% <0.00%> (+1.75%)	⬆️
joblib/_parallel_backends.py	91.91% <0.00%> (+3.30%)	⬆️

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[tomMoral]

It seems that the error is on our side no?
Following this discussion, it seems that we should simply switch to warning.catch_warning(record=True) instead of pytest.warns(None).

I will do a PR for this.

[ogrisel]

I started to do a PR but supporting both pytest 6 and pytest 7 at the same time without error in warning tests is complicated...

[tomMoral]

Even with the change proposed in the PR by scipy?

https://github.com/scipy/scipy/pull/15192/files

[ogrisel]

I had tried something more complex, then started to use this approach but then got a stalled pytest 7 problem after the test finish and I abandoned.

[ogrisel]

I did not investigate what was causing the staleness.

[tomMoral]

I tried to make a PR in #1264, if it stalls, I will try to investigate.