Upgrade Traefik to v3 and adapt matrix-media-repo role

`matrix-media-repo` is the only role that seems incompatible with the
changes introduced by Traefik v3, due to its use of `PathPrefix` with
regular expressions in a few places.

Regular expressions should now be used with `PathRegexp`, not
`PathPrefix`. Furthermore, they should follow the Golang regexp syntax,
as described in the migration guide:
https://doc.traefik.io/traefik/migration/v2-to-v3-details/#dynamic-configuration-changes

requirements.yml

@@ -70,7 +70,7 @@
   version: v1.0.0-0
   name: timesync
 - src: git+https://github.com/devture/com.devture.ansible.role.traefik.git
-  version: v2.11.4-0
+  version: v3.0.4-1
   name: traefik
 - src: git+https://github.com/devture/com.devture.ansible.role.traefik_certs_dumper.git
   version: v2.8.3-2