chore: remove AsRef impl from the StringLiteral macro since I don't like that behavior, reorganize it to prevent leaking proc-macro2 / syn / quote

string-literal/src/lib.rs

@@ -11,11 +11,11 @@ pub struct WrongLiteralError<S> {
 
 impl<S> Display for WrongLiteralError<S>
 where
-    S: AsRef<str>,
+    &'static str: for<'a> From<&'a S>,
 {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let Self { actual, expected } = self;
-        let expected_str = expected.as_ref();
+        let expected_str = <&'static str>::from(&expected);
 
         write!(f, "expected {expected_str:?} but got {actual:?}")
     }