DataFrame.pct_change typing for None missing

[loicdiridollou]

Describe the bug
A clear and concise description of what the bug is.
For the pd.DataFrame.pct_change the documentation allows the None method but the typing only supports str.
This results in an error from pyright to be raised.

To Reproduce

1. Provide a minimal runnable pandas example that is not properly checked by the stubs.
2. Indicate which type checker you are using (mypy or pyright).
3. Show the error message received from that type checker while checking your example.

df = pd.DataFrame({"x": [1, 2, 2, 3, 3], "y": [10, 20, 30, 40, 50]})
df.pct_change(fill_method=None)

This example will yield the error:

error: Argument "fill_method" to "pct_change" of "DataFrame" has incompatible type "None"; expected "str"  [arg-type]

While the documentation allows for None:

Please complete the following information:

• OS: MacOs
• OS Version Sonoma 14
• python version 3.12.4
• version of type checker 1.1.378
• version of installed pandas-stubs v2.2.2.240807

Additional context
Add any other context about the problem here.