LibWeb: Mark URLSearchParams::to_string() as const

Author: https://github.com/kennethmyhra
Commit: 1b9f5fa28a
Pull-request: https://github.com/SerenityOS/serenity/pull/14595
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibWeb/URL/URLSearchParams.h

@@ -41,7 +41,7 @@ public:
 
     void sort();
 
-    String to_string();
+    String to_string() const;
 
     using ForEachCallback = Function<JS::ThrowCompletionOr<void>(String const&, String const&)>;
     JS::ThrowCompletionOr<void> for_each(ForEachCallback);