fix: drop HEALTHCHECK + bind nginx ipv4+ipv6

Dockerfile

@@ -3,4 +3,3 @@ COPY nginx.conf /etc/nginx/conf.d/default.conf
 COPY index.html /usr/share/nginx/html/index.html
 COPY designs /usr/share/nginx/html/designs
 EXPOSE 80
-HEALTHCHECK --interval=30s --timeout=3s CMD wget -qO- http://localhost/ >/dev/null || exit 1

nginx.conf

@@ -1,5 +1,6 @@
 server {
   listen 80 default_server;
+  listen [::]:80 default_server;
   server_name _;
   root /usr/share/nginx/html;
   index index.html;