Upgrade to Python 3.11.x

[benfrancis]

Upgrade the version of Python which ships with WebThings Gateway, in:

• Docker image
• Snap package

See also: #2989

[benfrancis]

I suggest version 3.11.2, which is the current version of python3 that comes with Debian Bookworm (upon which I am basing the Docker image for WebThings Gateway 2.0).