fix: set nginx port to 80 to resolve variable substitution error

nginx.conf

@@ -1,7 +1,7 @@
 server {
     listen 80;
-    server_name localhost;
-    root /usr/share/nginx/html;
+    server_name _;
+    root /app;
     index index.html;
 
     # GZIP Compression

nginx.template.conf

@@ -1,5 +1,5 @@
 server {
-    listen ${PORT};
+    listen 80;
     server_name _;
     root /app;
     index index.php index.html index.htm;