fix compiler error round 2

Author: HTGAzureX1212

compiler/rustc_hir_analysis/src/structured_errors/missing_cast_for_variadic_arg.rs

@@ -54,13 +54,13 @@ impl<'tcx> StructuredDiagnostic<'tcx> for MissingCastForVariadicArg<'tcx, '_> {
             } else {
                 err.span_suggestion(
                     self.span,
-                    &format!("cast the value to `{}`", self.cast_ty),
+                    format!("cast the value to `{}`", self.cast_ty),
                     format!("{} as {}", snippet, self.cast_ty),
                     Applicability::MachineApplicable,
                 );
             }
         } else {
-            err.help(&format!("cast the value into `{}`", self.cast_ty));
+            err.help(format!("cast the value into `{}`", self.cast_ty));
         }
 
         err