Remove temporary CVE-2026-7210 exception after fixed Python 3.10 release #10

The Python 3.10.21 image is returning to the official upstream interpreter instead of rebuilding CPython with a local XML hash-salt backport. A temporary Grype exception for CVE-2026-7210 is limited to the python binary package at version 3.10.21. This accepts the outstanding vulnerability; it does not remediate it.

Remove the exception once an official Python 3.10 Alpine image includes the upstream fix (expected in Python 3.10.22; verify inclusion before removing the exception).

• Update the Python 3.10 image version to the fixed upstream release.
• Confirm the release includes the upstream XML hash-salt fix.
• Remove the CVE-2026-7210 rule from .grype.yaml; delete the file if no rules remain.
• Build and test the supported Python 3.10 variants on amd64 and arm64, and verify Grype passes without the exception.