As discussed in
https://mail.python.org/archives/list/numpy-discussion@python.org/thread/UKZJACAP5FUG7KP2AQDPE4P5ADNWLOHZ/

This flag was always meant to be temporary, and cleaning it up is
long overdue.

NumPy switched to using pytest in 2018 and nose has been unmaintained
for many years. We have kept NumPy's nose support to avoid breaking
downstream projects who might have been using it and not yet switched to
pytest or some other testing framework. With the arrival of Python 3.12,
unpatched nose will raise an error. It it time to move on.

Decorators removed

- raises
- slow
- setastest
- skipif
- knownfailif
- deprecated
- parametrize
- _needs_refcount

These are not to be confused with pytest versions with similar names,
e.g., pytest.mark.slow, pytest.mark.skipif, pytest.mark.parametrize.

Functions removed

- Tester
- import_nose
- run_module_suite

In some cases, the replacement is clearly not what is intended,
in those (where setup was called explicitly), I mostly renamed
`setup` to `_setup`.
The `test_ccompile_opt` is a bit confusing, so left it right now
(this will probably fail)

ENH: Ensure that assertion of unsigned dtypes does not return results

Fixes #9542

Co-authored-by: Bas van Beek <43369155+BvB93@users.noreply.github.com>