Bump python from 3.9.2-slim to 3.9.4-slim
Bump python from 3.9.2-slim to 3.9.4-slim

Bumps python from 3.9.2-slim to 3.9.4-slim.

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
mozilla/ichnaea,mozilla/ichnaea,mozilla/ichnaea,mozilla/ichnaea