Always set X-Forwarded-Proto to avoid mixed content warnings

This fixes mixed content warnings I've been getting when loading album covers. As documented in funkwhale#901 (closed) and https://dev.funkwhale.audio/funkwhale/funkwhale/-/merge_requests/237 , the X-Forwarded-Proto header needs to be set to https so album covers will be loaded securely, even when we have a TLS terminating proxy.

templates/funkwhale_proxy.conf.j2

@@ -2,8 +2,8 @@
 proxy_set_header Host $host;
 proxy_set_header X-Real-IP $remote_addr;
 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
-{% if not funkwhale_nginx_tls_termination -%}
 proxy_set_header X-Forwarded-Proto $scheme;
+{% if not funkwhale_nginx_tls_termination -%}
 proxy_set_header X-Forwarded-Host $host:$server_port;
 proxy_set_header X-Forwarded-Port $server_port;
 proxy_redirect off;