Bump node from 16.6.1-slim to 16.8.0-slim in /docker (from PR #2402)
Bump node from 16.6.1-slim to 16.8.0-slim in /docker (from PR #2402)

Bumps node from 16.6.1-slim to 16.8.0-slim.

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