Move to Python 3.9 for Dockerfile and CI

What's Changed

• Remove "<", ">" from default uninstallReason by @MRawlings in #137
• New sample to list KB category contents by @jofegan in #138
• 2024 Dockerfile updates & Python 3.9 by @jofegan in #139

Full Changelog: v3.4.0...v3.4.1