[3.12] gh-125893: Add type check for category argument in warnings.simplefilter and warnings.filterwarning

[hasrat17]

This PR addresses gh-125893 by adding a type check for the category argument in warnings.simplefilter and warnings.filterwarning,

Previously, warnings.filterwarnings correctly raised an error when the category argument was not a class, but warnings.simplefilter accepted invalid types without raising any error. This inconsistency could lead to confusion and improper warning filtering.

Both warnings.simplefilter and warnings.filterwarning were not raising any warnings while ran with python -O but now this is also handled.

$ ./amd64/python.exe -O -c "import warnings; warnings.resetwarnings(); warnings.simplefilter('default', category='Hello');  print(warnings.filters)"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Users\hasra\OneDrive\Documents\opensource\cpython\Lib\warnings.py", line 182, in simplefilter
    raise TypeError("category must be a Warning subclass, "
TypeError: category must be a Warning subclass, not 'str'

./amd64/python.exe -O -c "import warnings; warnings.resetwarnings(); warnings.filterwarnings('ignore', category=Warning); warnings.filterwarnings('ignore', category='Hello'); print(warnings.filters)"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Users\hasra\OneDrive\Documents\opensource\cpython\Lib\warnings.py", line 149, in filterwarnings
    raise TypeError("category must be a Warning subclass, "
TypeError: category must be a Warning subclass, not 'str'

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[picnixz]

Thanks for the PR but could you instead create a branch that is checked out from main, make your changes, then open a PR against main instead? we'll take care of backporting the changes to 3.13+ (3.12 won't get fixed as it's security only)

[brianschubert]

Closing since #136305 has been opened against main

[hasrat17]

As suggested by @picnixz I opened #136305 against main please review it. Thanks