remove redundant imports

detects redundant imports that can be eliminated.

for rust-lang#117772 :

In order to facilitate review and modification, split the checking code and
removing redundant imports code into two PR.

Author: surechen

crates/stdx/src/anymap.rs

@@ -17,7 +17,6 @@
 
 #![warn(missing_docs, unused_results)]
 
-use core::convert::TryInto;
 use core::hash::Hasher;
 
 /// A hasher designed to eke a little more speed out, given `TypeId`’s known characteristics.