Fix self-building for Coturn

689dcea773 wasn't enough. The `upstream/..` tags are
just upstream sources, without the alpine-based Dockerfile.
We need to use the `docker/..` tags for that (or `master`)

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1032

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1023

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1009

roles/matrix-coturn/defaults/main.yml

@@ -2,7 +2,7 @@ matrix_coturn_enabled: true
 
 matrix_coturn_container_image_self_build: false
 matrix_coturn_container_image_self_build_repo: "https://github.com/coturn/coturn"
-matrix_coturn_container_image_self_build_repo_version: "upstream/{{ matrix_coturn_version }}"
+matrix_coturn_container_image_self_build_repo_version: "docker/{{ matrix_coturn_version }}-r0"
 matrix_coturn_container_image_self_build_repo_dockerfile_path: "docker/coturn/alpine/Dockerfile"
 
 matrix_coturn_version: 4.5.2