Upgrade nginx (1.19.3 -> 1.19.4)

roles/matrix-nginx-proxy/defaults/main.yml

@@ -3,7 +3,7 @@ matrix_nginx_proxy_enabled: true
 # We use an official nginx image, which we fix-up to run unprivileged.
 # An alternative would be an `nginxinc/nginx-unprivileged` image, but
 # that is frequently out of date.
-matrix_nginx_proxy_docker_image: "nginx:1.19.3-alpine"
+matrix_nginx_proxy_docker_image: "nginx:1.19.4-alpine"
 matrix_nginx_proxy_docker_image_force_pull: "{{ matrix_nginx_proxy_docker_image.endswith(':latest') }}"
 
 matrix_nginx_proxy_base_path: "{{ matrix_base_data_path }}/nginx-proxy"