Fix warnings from clippy 1.79

Author: Philippe-Cholet

src/extrema_set.rs

@@ -1,4 +1,3 @@
-#![cfg(feature = "use_alloc")]
 use alloc::{vec, vec::Vec};
 use std::cmp::Ordering;
 

src/grouping_map.rs

@@ -1,5 +1,3 @@
-#![cfg(feature = "use_std")]
-
 use crate::{
     adaptors::map::{MapSpecialCase, MapSpecialCaseFn},
     MinMaxResult,

tests/zip.rs

@@ -20,7 +20,7 @@ fn test_zip_longest_size_hint() {
     let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
     let v2 = &[10, 11, 12];
 
-    assert_eq!(c.zip_longest(v.iter()).size_hint(), (std::usize::MAX, None));
+    assert_eq!(c.zip_longest(v.iter()).size_hint(), (usize::MAX, None));
 
     assert_eq!(v.iter().zip_longest(v2.iter()).size_hint(), (10, Some(10)));
 }