net/traefik: Update to upstream release 3.7.8
Details:
- Bug-, doc- and security fixes, see https://github.com/traefik/traefik/releases/tag/v3.7.8
MFH: 2026Q3
Security: https://github.com/traefik/traefik/security/advisories/GHSA-cxjq-mrr5-89rv
https://github.com/traefik/traefik/security/advisories/GHSA-42cj-m3vj-89wv https://github.com/traefik/traefik/security/advisories/GHSA-qq9q-x9w4-chhj https://github.com/traefik/traefik/security/advisories/GHSA-8rxv-jg7p-wvg3
(cherry picked from commit e8b169b0e703f775410f757232af435a887074f7)