allow underscores in header

build/nginx/configuration/nginx.conf

@@ -28,6 +28,8 @@ http {
         '' "default-src 'self'; script-src 'self'; script-src-elem 'self'; script-src-attr 'self'; style-src 'self'; style-src-elem 'self'; style-src-attr 'self'; img-src 'self' data:; font-src 'self'; connect-src 'self'; frame-src 'self'; frame-ancestors 'self' https://scripts.zdv.uni-mainz.de; form-action 'self' metager.org metager.de";
     }
 
+    underscores_in_headers "on";
+    
     add_header "X-Frame-Options" "sameorigin";
     add_header "X-Content-Type-Options" "nosniff";
     add_header "ReferrerPolicy" "origin";