net/traefik: Update to upstream release 2.6.2, fix build on go 1.18

Details:

• Bugfix release, see https://github.com/traefik/traefik/releases/tag/v2.6.2
• Fixes build on go 1.18 (Extra patching our local tarball. The upstream 2.6.2 does not support build on go 1.18 without modifications.)

PR: 262859