Rollup merge of #103726 - TaKO8Ki:avoid-&str-to-string-conversions, r=compiler-errors

Avoid unnecessary `&str` to `String` conversions

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -507,7 +507,7 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
                                 _ => "aren't",
                             },
                         ),
-                        " else { todo!() }".to_string(),
+                        " else { todo!() }",
                         Applicability::HasPlaceholders,
                     );
                 }