Update Docker image versions

roles/matrix-server/defaults/main.yml

@@ -37,9 +37,9 @@ matrix_nginx_proxy_confd_path: "{{ matrix_nginx_proxy_data_path }}/conf.d"
 matrix_nginx_riot_web_data_path: "{{ matrix_base_data_path }}/riot-web"
 matrix_scratchpad_dir: "{{ matrix_base_data_path }}/scratchpad"
 
-docker_postgres_image: "postgres:9.6.5-alpine"
+docker_postgres_image: "postgres:9.6.6-alpine"
 docker_matrix_image: "silviof/docker-matrix:latest"
-docker_nginx_image: "nginx:1.13.5-alpine"
+docker_nginx_image: "nginx:1.13.7-alpine"
 docker_riot_image: "silviof/matrix-riot-docker:latest"
 docker_s3fs_image: "xueshanf/s3fs:latest"