Fix DeprecationWarning from scipy.sparse.base

[covertg]

Motivation for these changes

Scipy versions after 1.8 deprecated a bunch of namespaces in order to clarify the intended public namespaces: https://docs.scipy.org/doc/scipy/release.1.8.0.html

Turns out that the annotation on sparse.basic.as_symbolic_sparse accesses a "private" scipy namespace, so importing pytensor when a newer scipy is installed will yield the following warning.

>>> import scipy, warnings
>>> scipy.__version__
'1.10.0'
>>> warnings.resetwarnings()
>>> import pytensor
/home/cove/pytensor/pytensor/sparse/basic.py:132: DeprecationWarning: Please use `spmatrix` from the `scipy.sparse` namespace, the `scipy.sparse.base` namespace is deprecated.
  @_as_symbolic.register(scipy.sparse.base.spmatrix)

Not a big deal (and numba-scipy currently requires scipy<=1.7.3), but newer scipy happened to be installed on my system and this had been bugging me. :D

Checklist

• Explain motivation and implementation 👆
• Make sure that the pre-commit linting/style checks pass.
• Link relevant issues, preferably in nice commit messages.
• The commits correspond to relevant logical changes. Note that if they don't, we will rewrite/rebase/squash the git history before merging.
• Are the changes covered by tests and docstrings?
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(Not much more to note, pretty simple!)

[codecov-commenter]

Codecov Report

Merging #214 (3c8cde2) into main (aa7ce08) will not change coverage.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #214   +/-   ##
=======================================
  Coverage   80.08%   80.08%           
=======================================
  Files         170      170           
  Lines       45260    45260           
  Branches     9631     9631           
=======================================
  Hits        36245    36245           
  Misses       6797     6797           
  Partials     2218     2218           

Impacted Files	Coverage Δ
pytensor/sparse/basic.py	82.54% <100.00%> (ø)

[ricardoV94]

Thanks, I was also bugged by it