Apply ruff/flake8-pytest-style preview rules (PT)

[DimitriPapadopoulos]

TODO:

• Unit tests and/or doctests in docstrings
• Tests pass locally
• Docstrings and API docs for any new/modified user-facing classes and functions
• Changes documented in docs/release.rst
• Docs build locally
• GitHub Actions CI passes
• Test coverage to 100% (Codecov passes)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.91%. Comparing base (fed46e5) to head (445bcc0).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #606   +/-   ##
=======================================
  Coverage   99.91%   99.91%           
=======================================
  Files          59       59           
  Lines        2328     2328           
=======================================
  Hits         2326     2326           
  Misses          2        2           

Files with missing lines	Coverage Δ
numcodecs/tests/test_entrypoints.py	100.00% <100.00%> (ø)
numcodecs/tests/test_pcodec.py	100.00% <100.00%> (ø)
numcodecs/tests/test_shuffle.py	100.00% <100.00%> (ø)

[dstansby]

👍 when the merge conflict is fixed