Backport of Prepare for pandas 2.0 (#2434) onto 1.9.x (#2435)
* Prepare for pandas 2.0 (#2434)
* is_categorical -> is_categorical_dtype
* cat.replace(to_remove, np.nan) -> cat.remove_categories(to_remove)
* df1.append(df2) -> pd.concat([df1, df2])
* Series.iteritems -> Series.items
* Fix indexing a pandas object with a set in score genes
* Release notes
(cherry picked from commit 0692ef9ea30335b95f7e7f9aab7be856469d9f35)
* Fix anndata-dev test
* anndata-dev compatibility
* Prep 1.9.3
* Fix pr reference
