MNT Use full flake8 rather than flake8_diff.sh

[lesteve]

Easier to understand, easier to run locally, flake8 --diff has been removed in flake8>=6 see #1383. There are not that many flake8 violations to fix.

[tomMoral]

I think this is a nice idea so it will be easier to maintain in the long run.
A couple of comments but otherwise LGTM

[tomMoral]

a few more typo

[codecov]

Codecov Report

Patch coverage: 80.76% and project coverage change: -0.09 ⚠️

Comparison is base (a007d79) 94.87% compared to head (fd1dd6c) 94.78%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1415      +/-   ##
==========================================
- Coverage   94.87%   94.78%   -0.09%     
==========================================
  Files          46       45       -1     
  Lines        6901     6889      -12     
==========================================
- Hits         6547     6530      -17     
- Misses        354      359       +5     

Impacted Files	Coverage Δ
joblib/__init__.py	100.00% <ø> (ø)
joblib/executor.py	100.00% <ø> (ø)
joblib/memory.py	95.52% <0.00%> (+0.26%)	⬆️
joblib/numpy_pickle_compat.py	91.08% <ø> (ø)
joblib/test/test_func_inspect_special_encoding.py	50.00% <ø> (ø)
joblib/test/test_hashing.py	99.06% <ø> (-0.01%)	⬇️
joblib/test/test_numpy_pickle_compat.py	100.00% <ø> (ø)
joblib/test/test_numpy_pickle_utils.py	100.00% <ø> (ø)
joblib/test/test_parallel.py	97.13% <ø> (-0.01%)	⬇️
joblib/logger.py	86.84% <25.00%> (ø)
... and 6 more

... and 2 files with indirect coverage changes

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[tomMoral]

LGTM, the failure does not seem related.
Merging and hoping this won't cause too much troubles with other PRs.