Add Python 3.13-3.16 support

[KaranocaVe]

Summary

• add Python 3.13 through 3.16 package classifiers without changing the existing Python >= 3.6 requirement
• extend Linux CI through Python 3.16 development builds and Windows CI through Python 3.14
• update the checkout and Python setup actions, retain the legacy NVML compatibility job on Ubuntu 22.04, and replace direct pip/pytest invocations with python -m
• document the expanded compatibility range

Why

The package source already runs on current and upcoming Python versions, but the published metadata and CI matrix stopped at Python 3.12. The workflow also referenced the retired Ubuntu 20.04 runner and old action releases, preventing it from serving as a reliable compatibility signal.

This change extends the tested range while preserving the existing minimum supported Python version.

Validation

• Python 3.12.11, 3.13.11, 3.14.6, and 3.15.0b3 on macOS: 13 passed, 1 xfailed on each version
• Python 3.14.4 on Linux with eight RTX 4090 GPUs: 13 passed, 1 xfailed; live NVML query returned all eight GPUs
• CPython 3.16.0a0 built from main on Linux: 13 passed, 1 xfailed; live NVML query returned all eight GPUs
• wheel and sdist built under Python 3.15 and passed twine check
• wheel metadata confirmed Requires-Python: >=3.6 and classifiers through Python 3.16
• GitHub Actions workflow passed actionlint and YAML parsing