net/traefik: Update to upstream release 2.8.0
Details:
- New release on the 2.8 branch, see https://github.com/traefik/traefik/releases/tag/v2.8.0
- No known breaking configuration changes, see https://doc.traefik.io/traefik/migration/v2/
MFH: 2022Q3
(cherry picked from commit fd19387d6ccbc3a16ae0a1ab29fec27b2aebb541)