net/traefik: Update to upstream release 3.6.12

Details:

• Bugfix release, see https://github.com/traefik/traefik/releases/tag/v3.6.12
• Includes security fixes:
  • BasicAuth/DigestAuth Identity Spoofing via Non-Canonical headerField
  • Update dependency for a previously vulnerable gRPC-go implementation

MFH: 2026Q1
Security: CVE-2026-33433

		CVE-2026-33186

(cherry picked from commit 3c1a911846043a4d046d8a985393fa04273f52ce)