process scheme from reverse proxy correctly

docker/configs/nginx.conf

@@ -1,11 +1,15 @@
+map $http_x_forwarded_proto $forwarded_scheme {
+        default $scheme;
+        http http;
+        https https;
+}
+
 server {
         listen 80 default_server;
         listen [::]:80 default_server;
 
         root /var/www/mapguesser/public;
-
         index index.php index.html index.htm index.nginx-debian.html;
-
         server_name mapguesser-dev.ch;
 
         location / {
@@ -15,6 +19,7 @@ server {
         location ~ \.php$ {
                 include snippets/fastcgi-php.conf;
                 fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
+                fastcgi_param REQUEST_SCHEME $forwarded_scheme;
         }
 
         location ~ /\.ht {