PyO3 0.17.3

This release confirms support for Python 3.11 in PyO3.

(Previous versions of PyO3 0.17 had been tested against release candidates of Python 3.11 and no Python 3.11 fixes have been added since 0.17.0, so all PyO3 0.17 versions should in practice be fine to use with Python 3.11.)

In addition, some other small additions and fixes have been added on top of PyO3 0.17.2.

Thank you to the following users for the improvements:

@adamreichold
@ctb
@datapythonista
@davidhewitt
@messense
@saethlin