Work around deprecation of str::trim_left_matches

serde_derive/src/internals/attr.rs

@@ -95,7 +95,11 @@ pub struct Name {
     deserialize: String,
 }
 
+#[allow(deprecated)]
 fn unraw(ident: &Ident) -> String {
+    // str::trim_start_matches was added in 1.30, trim_left_matches deprecated
+    // in 1.33. We currently support rustc back to 1.15 so we need to continue
+    // to use the deprecated one.
     ident.to_string().trim_left_matches("r#").to_owned()
 }