Fix connection header (#1252)

nginx/nginx.conf

@@ -72,7 +72,7 @@ http {
       proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
       proxy_set_header X-Forwarded-Proto $scheme;
       proxy_set_header Upgrade $http_upgrade;
-      proxy_set_header Connection "upgrade";
+      proxy_set_header Connection $connection_upgrade;
       proxy_set_header Host $host;
 
       rewrite /api/(.*) /$1 break;
@@ -94,7 +94,7 @@ http {
       proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
       proxy_set_header X-Forwarded-Proto $scheme;
       proxy_set_header Upgrade $http_upgrade;
-      proxy_set_header Connection "upgrade";
+      proxy_set_header Connection $connection_upgrade;
       proxy_set_header Host $host;
 
       proxy_pass ${IMMICH_WEB_SCHEME}web;