(chore): adopt scientific python deprecation schedule

[ilan-gold]

This PR forces us to adopt the scientific python deprecation schedule as much as possible. It also cleans up our use of spmatrix/sparray because of the bumping of scipy.sparse so that handling sparray is always done via a concrete class

• Closes (chore): clean up use of spmatrix and sparray #1649
• Tests added
• Release note added (or unnecessary)

[codecov]

Codecov Report

Attention: Patch coverage is 97.29730% with 2 lines in your changes missing coverage. Please review.

Project coverage is 83.67%. Comparing base (7fc66bb) to head (8b5048e).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/anndata/_core/merge.py	95.65%	1 Missing ⚠️
src/anndata/tests/helpers.py	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1768      +/-   ##
==========================================
- Coverage   83.84%   83.67%   -0.17%     
==========================================
  Files          41       40       -1     
  Lines        6288     6242      -46     
==========================================
- Hits         5272     5223      -49     
- Misses       1016     1019       +3     

Files with missing lines	Coverage Δ
src/anndata/__init__.py	100.00% <100.00%> (ø)
src/anndata/_core/aligned_mapping.py	93.41% <100.00%> (-0.03%)	⬇️
src/anndata/_core/anndata.py	82.61% <100.00%> (ø)
src/anndata/_core/index.py	93.60% <100.00%> (ø)
src/anndata/_core/raw.py	75.88% <100.00%> (ø)
src/anndata/_core/sparse_dataset.py	92.14% <100.00%> (ø)
src/anndata/_core/storage.py	100.00% <100.00%> (ø)
src/anndata/_io/h5ad.py	92.68% <ø> (ø)
src/anndata/_io/specs/lazy_methods.py	97.80% <ø> (ø)
src/anndata/_io/specs/methods.py	88.36% <100.00%> (ø)
... and 8 more

[flying-sheep]

Looks really good! So many simplifications. I have a few minor questions and nitpicks apart from #1768 (comment), that’s all.