feat: add support for Python 3.11

[ziegenberg]

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Fixes #1972 🦕

This also fixes a FutureWarning from pandas

In a future version of pandas all arguments of StringMethods.rsplit except for the argument 'pat' will be keyword-only.

This also fixes a deprecation happening in Python 3.11

DeprecationWarning: inspect.getargspec() is deprecated since Python 3.0

With Python 3.11 inspect.getargspec() was removed. The recommendation is to use inspect.getfullargspec().

See: https://docs.python.org/3.10/library/inspect.html#inspect.getargspec

Deprecated since version 3.0: Use getfullargspec() for an updated API
that is usually a drop-in replacement, but also correctly handles
function annotations and keyword-only parameters.