Fix self-building for Coturn

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1158

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: "docker/{{ matrix_coturn_version }}-r2"
+matrix_coturn_container_image_self_build_repo_version: "docker/{{ matrix_coturn_version }}"
 matrix_coturn_container_image_self_build_repo_dockerfile_path: "docker/coturn/alpine/Dockerfile"
 
 matrix_coturn_version: 4.5.2-r2