Fix deprecation warning on Python 3.12
`Constant.n` is now deprecated for removal in 3.14; it appears that `Constant.value` has existed since at least 3.9.

- [n/a] closes #xxxx (Replace xxxx with the GitHub issue number)
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [n/a] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

I already have a PR for this #53743.

Thanks for the effort though. Thanks for the PR, but since this is covered in https://github.com/pandas-dev/pandas/pull/53743 will close in favor of that PR Oops, thought I looked for existing ones; not sure why I didn't find it earlier.