gh-37583: Workaround warning in cython 3.0.9 (#37560)
A new warning in cython 3.0.9 breaks doctests
https://github.com/cython/cython/pull/5999.
We filter this warning at runtime, as a quick workaround for 10.3.
For the future, we will need to remove the `noexcept` in question. Note
that these were mostly added in #36507 guided by a different warning
which is not quite right (see
https://github.com/cython/cython/pull/5999#issuecomment-1986868208).
This has to be done with some care: about 2/3rds of the `noexcept` have
to be removed, but the other 1/3rd has to be kept. These changes are no-
ops as long as we use `legacy_implicit_noexcept=True` but it's important
to get it right before removing the legacy option. Hopefully we'll soon
have a version of cython which gives correct warnings so it's possible
to eliminate both types of warnings. Once there are no warnings left, we
can proceed to remove the legacy option.
### :memo: Checklist
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- [x] The description explains in detail what this PR is about.
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Fixes: #37560
URL: https://github.com/sagemath/sage/pull/37583
Reported by: Gonzalo Tornaría
Reviewer(s):
