REGR: Fixed handling of Categorical in cython ops
Fixed by falling back to the wrapped Python version when the cython
version raises NotImplementedError.

Closes https://github.com/pandas-dev/pandas/issues/31450
LGTM.  Is this the long-term solution? I'm not really sure to be honest.  this looks good. it should be the long-term, until we fully handle EAs in cython.