requests: allow str and bytes for fileobj in files parameter

[milanboers]

Some people are having issues with this one, see #7724

Documentation says to pass a "file-like-object". Implementation allows for str, bytes, bytearray or anything that implements .read().
Left bytearray out for now because urllib3 documents str and bytes as valid in RequestField in the next major version.

Resolves #7724

[AlexWaygood]

The implementation looks like it can be str, bytes, or anything with a .read() method: https://github.com/psf/requests/blob/31a89d9c8463c3394ca00f408f4b86d814421a09/requests/models.py#L160-L161

Rather than using IO[Any], we could make it even more permissive, and just use _typeshed.SupportsRead:

typeshed/stdlib/_typeshed/__init__.pyi

Lines 180 to 181 in 1f2a970

	class SupportsRead(Protocol[_T_co]):
	def read(self, __length: int = ...) -> _T_co: ...

[milanboers]

Good one, done! Kept the IO in _Data as-is, because it also needs .tell() there.

[AlexWaygood]

I've confirmed that this annotation will allow objects with a .read() returning bytes, and objects with a .read() returning str: https://mypy-play.net/?mypy=latest&python=3.10&gist=c5afaf626edee4068ca05bc806f33f64

[AlexWaygood]

Thanks!