docker: Multiple fixes

[MattKobayashi]

Change Summary

• Update Debian base image to 12
• Add --break-system-packages option to pip3 install command
• Remove chmod a+s from Dockerfile (newer versions of gosu in particular don't support this)
• Add sudo to relevant commands in entrypoint.sh
• Add UID_MIN key to adduser command (allows the container to run on MacOS)
• Formatting and spelling fixes

Related Task(s)

Related PR(s)

Backport

• sagitta
• equuleus

Checklist:

• [x] I have read the CONTRIBUTING document