Bump kombu from 4.6.7 to 4.6.8 (from PR #1999)
Bump kombu from 4.6.7 to 4.6.8 (from PR #1999)

Bumps [kombu](https://kombu.readthedocs.io) from 4.6.7 to 4.6.8.

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>

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