hotfix: add missing import

Rejyr · Rejyr · commit 32e445af7499 · 2022-08-22T08:24:14.000-04:00
diff --git a/compiler/rustc_lint/src/errors.rs b/compiler/rustc_lint/src/errors.rs
@@ -1,5 +1,5 @@
 use rustc_macros::{SessionDiagnostic, SessionSubdiagnostic};
-use rustc_span::Span;
+use rustc_span::{Span, Symbol};
 
 #[derive(SessionDiagnostic)]
 #[error(lint::malformed_attribute, code = "E0452")]
