Add unit tests for factorial.py

[QasimUmarKhan]

Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".

[cclauss]

I added a few things:

1. Use pytest instead of unittest -- uvx --python=3.12 unittest2pytest --write maths/test_factorial.py
2. Use @pytest.mark.parametrize() to test both factorial() and factorial_recursive().
3. Fix an unrelated test failure in web_programming/current_stock_price.py

These functions were already tested via these doctests:

Python/maths/factorial.py

Lines 10 to 26 in 7665ba5

	>>> import math
	>>> all(factorial(i) == math.factorial(i) for i in range(20))
	True
	>>> factorial(0.1)
	Traceback (most recent call last):
	...
	ValueError: factorial() only accepts integral values
	>>> factorial(-1)
	Traceback (most recent call last):
	...
	ValueError: factorial() not defined for negative values
	>>> factorial(1)
	1
	>>> factorial(6)
	720
	>>> factorial(0)
	1

[cclauss]

@lighting9999 Let's use this PR to make the fixes to the failing tests in web_programming/current_stock_price.py.

We use httpx instead of requests.

• Replace dependency requests with httpx #12732