Bump python from 3.9.6-slim to 3.9.7-slim in /docker (from PR #2401)
Bump python from 3.9.6-slim to 3.9.7-slim in /docker (from PR #2401)

Bumps python from 3.9.6-slim to 3.9.7-slim.

mozilla-services/tecken,mozilla-services/tecken,mozilla-services/tecken,mozilla-services/tecken