Upgrade pytype support to include Python 3.10 and 3.11

[davidfstr]

trycast is currently tested against pytype 2022.3.21, which supports Python 3.8-3.9. The latest version of pytype, 2024.04.11, supports Python 3.8-3.11

Please upgrade pytype to a more-modern version that includes Python 3.10 and 3.11 support.

[davidfstr]

Instead of enhancing pytype support, consider dropping support entirely in favor of Google's new upcoming typechecker, pending announcement as of 2025-05-18.