Add iter_at_least and iter_at_most feature flags to core/lib.rs

Author: Folyd

library/core/src/lib.rs

@@ -165,6 +165,8 @@
 #![feature(no_niche)] // rust-lang/rust#68303
 #![feature(unsafe_block_in_unsafe_fn)]
 #![feature(int_error_matching)]
+#![feature(iter_at_least)]
+#![feature(iter_at_most)]
 #![deny(unsafe_op_in_unsafe_fn)]
 
 #[prelude_import]