No need to whitelist E0750 anymore

Author: GuillaumeGomez

src/tools/tidy/src/error_codes_check.rs

@@ -17,7 +17,7 @@ const WHITELIST: &[&str] = &[
 
 // Some error codes don't have any tests apparently...
 const IGNORE_EXPLANATION_CHECK: &[&str] =
-    &["E0570", "E0601", "E0602", "E0639", "E0729", "E0749", "E0750", "E0751"];
+    &["E0570", "E0601", "E0602", "E0639", "E0729", "E0749", "E0750"];
 
 fn check_error_code_explanation(
     f: &str,