net/traefik: Update to upstream version 2.7.0

Details:

• New release on the 2.7 branch, see https://github.com/traefik/traefik/releases/tag/v2.7.0
• Configuration files are compatible with 2.6.1 and later, no breaking changes went into the new branch, see https://github.com/traefik/traefik/releases/tag/v2.7.0

MFH: 2022Q2
(cherry picked from commit 10b61d9e02f21a67e76a9bdd370b46705336116e)