Filter DeprecationWarning in failing test for python 3.12

[cmarmo]

Dear maintainers,

it seems to me that the failing test in #522 and #512 is generated by a DeprecationWarning new in python 3.12.
This pull request fixes the test filtering DeprecationWarnings in that specific test.

Closes #512.
Closes #522.

Thank you for considering it.

[larsoner]

@cmarmo could you git cherry-pick 4deb459 or similar so we get 3.12 CIs running in this PR as well? #522 shows that they fail on main so we can close that PR and then merge this one when green.

[cmarmo]

Thanks @larsoner , indeed I wasn't sure about the project policies about python versions.

[larsoner]

I think we can properly fix this rather than by filtering the DeprecationWarning using ast.Constant in place of ast.NameConstant in our code (assuming I'm reading the ast stuff right). @cmarmo do you want to do it in this PR? If not I'm happy to merge this then open a quick PR myself to try it.

[cmarmo]

I'm afraid I probably need a deeper look at the code to understand what you are proposing... I was hoping to be helpful , but if you can offer a better fix you are likely to be more efficient than me ... :)

[larsoner]

Thanks @cmarmo !