Switch from &String to &str

tests/data.rs

@@ -26,7 +26,7 @@ fn check_invariants(url: &Url) {
 }
 
 
-fn run_parsing(input: &String, base: &String, expected: Result<ExpectedAttributes, ()>) {
+fn run_parsing(input: &str, base: &str, expected: Result<ExpectedAttributes, ()>) {
     let base = match Url::parse(&base) {
         Ok(base) => base,
         Err(message) => panic!("Error parsing base {:?}: {}", base, message)