enhance visualization func type hint

[zen-xu]

No description provided.

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[IvanIsCoding]

Thanks for your second contribution to rustworkx!

I will need to review this PR with more care. In the meantime @zen-xu can you sign the CLA? Otherwise we won't be able to merge your code. Thanks.

[coveralls]

Pull Request Test Coverage Report for Build 14953556689

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage remained the same at 95.236%

---

Files with Coverage Reduction	New Missed Lines	%
rustworkx-core/src/token_swapper.rs	5	97.0%

Totals
Change from base Build 14916993103:	0.0%
Covered Lines:	18733
Relevant Lines:	19670

---

💛 - Coveralls

[IvanIsCoding]

The matplotlib change LGTM, for graphviz I'd rather not step into using typing.Literal. The typing.overload is fine.

[IvanIsCoding]

I think you’ll need to run the code formatter. Either nox -eblack or just black rustworkx if you have it installed