COMP: Update CI best practices and Python 3.10+

[hjmjohnson]

Update CI workflows to current best practices: actions/checkout@v5, Python 3.10+ minimum, and ITKRemoteModuleBuildTestPackageAction@v5.4.6 with ITK wheel tags pinned to v5.4.5.

Note: Windows Python wheels may fail with ensurepip until ITKPythonPackage cuts a new release tag including the fix. C++ CI and Linux/macOS Python builds are unaffected.

Commits (3)

1. COMP: Update actions/checkout to v5
2. COMP: Update minimum Python version to 3.10+ — bump pyproject.toml and workflow matrix
3. COMP: Update action to v5.4.6 and ITK wheel tags to v5.4.5

Dropped commit

48fe55c ("COMP: Point itk-python-package-tag at main for Windows pip fix") was dropped — using itk-python-package-tag: 'main' fixed the Windows ensurepip issue but broke Linux Python wrapping due to CastXML incompatibility with gcc-toolset-14 in the latest manylinux container.

[hjmjohnson]

WIP: test-linux-notebooks blocked on upstream Python 3.9 default.

Same issue as InsightSoftwareConsortium/ITKSplitComponents#91 — the build-test-package-python.yml@v6.0b01 action defaults to Python 3.9 for notebook tests, but this wheel requires >=3.10. Fix submitted upstream: InsightSoftwareConsortium/ITKRemoteModuleBuildTestPackageAction#126.

All C++ builds and Python wheel builds pass. Once the upstream PR merges and CI re-runs, this PR should be green.