nixos/roundcube: fixed nginx configuration

the changes are required for oauth setups,
and are based on:
https://github.com/roundcube/roundcubemail/issues/8191#issuecomment-919850328

nixos/modules/services/mail/roundcube.nix

@@ -150,9 +150,13 @@ in
             root = cfg.package;
             index = "index.php";
             extraConfig = ''
-              location ~* \.php$ {
+              location ~* \.php(/|$) {
                 fastcgi_split_path_info ^(.+\.php)(/.+)$;
                 fastcgi_pass unix:${fpm.socket};
+
+                fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
+                fastcgi_param PATH_INFO       $fastcgi_path_info;
+
                 include ${config.services.nginx.package}/conf/fastcgi_params;
                 include ${pkgs.nginx}/conf/fastcgi.conf;
               }