fix: Restore RSS feed for comments in Rails 8

Fix template resolution by removing .rss suffix from action name.
Rails 8 now looks for index.rss.erb automatically when format is :rss.

Author: flemzord

app/controllers/comments_controller.rb

@@ -261,7 +261,7 @@ def index
           @title = "Private comments feed for #{@user.username}"
         end
 
-        render action: "index.rss", layout: false
+        render action: "index", layout: false
       }
     end
   end