Update dependencies

roles/matrix-server/defaults/main.yml

@@ -135,10 +135,10 @@ matrix_docker_image_postgres_v10: "postgres:10.5-alpine"
 matrix_docker_image_postgres_latest: "{{ matrix_docker_image_postgres_v10 }}"
 
 matrix_docker_image_synapse: "matrixdotorg/synapse:v0.33.5.1"
-matrix_docker_image_nginx: "nginx:1.15.3-alpine"
+matrix_docker_image_nginx: "nginx:1.15.5-alpine"
 matrix_docker_image_riot: "avhost/docker-matrix-riot:v0.16.4"
 matrix_docker_image_goofys: "cloudproto/goofys:latest"
-matrix_docker_image_coturn: "instrumentisto/coturn:4.5.0.7"
+matrix_docker_image_coturn: "instrumentisto/coturn:4.5.0.8"
 matrix_docker_image_mailer: "panubo/postfix:latest"
 matrix_docker_image_mxisd: "kamax/mxisd:1.1.1"
 matrix_docker_image_mautrix_telegram: "tulir/mautrix-telegram:v0.3.0"