nginx: replace $http_host by $host, cf https://github.com/yandex/gixy…

…/blob/master/docs/en/plugins/hostspoofing.md / Credit to A.Wolski

conf/nginx/redirect_to_admin.conf

@@ -1,3 +1,3 @@
 location / {
-    return 302 https://$http_host/yunohost/admin;
+    return 302 https://$host/yunohost/admin;
 }

conf/nginx/server.tpl.conf

@@ -25,7 +25,7 @@ server {
     {# Note that this != "False" is meant to be failure-safe, in the case the redrect_to_https would happen to contain empty string or whatever value. We absolutely don't want to disable the HTTPS redirect *except* when it's explicitly being asked to be disabled. #}
     {% if redirect_to_https != "False" %}
     location / {
-        return 301 https://$http_host$request_uri;
+        return 301 https://$host$request_uri;
     }
     {# The app config snippets are not included in the HTTP conf unless HTTPS redirect is disabled, because app's location may blocks will conflict or bypass/ignore the HTTPS redirection. #}
     {% else %}

conf/nginx/yunohost_api.conf.inc

@@ -4,7 +4,7 @@ location /yunohost/api/ {
     proxy_http_version 1.1;
     proxy_set_header Upgrade $http_upgrade;
     proxy_set_header Connection "upgrade";
-    proxy_set_header Host $http_host;
+    proxy_set_header Host $host;
 
     {% if webadmin_allowlist_enabled == "True" %}
     {% for ip in webadmin_allowlist.split(',') %}