[deps] Remove Python 3.10 (EOL) #182

Python 3.10 has reached end of life. Remove Python 3.10 (EOL) from the supported versions, CI matrix, and package metadata, and remove or refactor any code that exists only to support Python 3.10 or older (e.g. version checks, compatibility shims or backport dependencies).

The CI matrix and package metadata already require Python 3.11 or later, but the PyPI workflow still uses Python 3.10. Update the PyPI workflow and any remaining references accordingly.