Re-evaluate if `typing_extensions` is still needed as a vendored dependency for `pkg_resources`

> This (`typing_extensions`) was not listed. The `vendored.txt` file says the following:
>
> ```
> # required for platformdirs on Python < 3.8
> typing_extensions==4.4.0
> ```
>
> But now we removed support to Python < 3.8, so I guess we can remove this vendored dependency?

_Originally posted by @abravalheri in https://github.com/pypa/setuptools/pull/4320#discussion_r1574742424_
            