Remove Python 3.9 support and the legacy retworkx import

[IvanIsCoding]

In short, this PR:

• Moves the build from 3.9 ABI to 3.10 ABI
• Removes Python 3.9 from GitHub actions
• Bumps Python in CI: 3.10->3.12 to avoid having to do bumps when 3.10 reaches EoL
• Removes the legacy retworkx shim
• Run tests with the Python 3.14 RC. I will add a release note for 3.14 once it's formally released and we are closer to the 0.18.0 release

[coveralls]

Pull Request Test Coverage Report for Build 18638972022

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.01%) to 94.187%

---

Files with Coverage Reduction	New Missed Lines	%
rustworkx-core/src/generators/random_graph.rs	2	69.81%

Totals
Change from base Build 18637670573:	-0.01%
Covered Lines:	18260
Relevant Lines:	19387

---

💛 - Coveralls

[IvanIsCoding]

I bumped ruff to lint for Python 3.10 and it found some fixes that are only available for 3.10+.