refactor(tests): replace deprecated numeric api with primitive one

Author: tottoto

src/header/value.rs

@@ -411,7 +411,7 @@ macro_rules! from_integers {
             let val = HeaderValue::from(n);
             assert_eq!(val, &n.to_string());
 
-            let n = ::std::$t::MAX;
+            let n = $t::MAX;
             let val = HeaderValue::from(n);
             assert_eq!(val, &n.to_string());
         }

tests/header_map.rs

@@ -60,7 +60,7 @@ fn with_capacity_overflow() {
 fn reserve_overflow() {
     // See https://github.com/hyperium/http/issues/352
     let mut headers = HeaderMap::<u32>::with_capacity(0);
-    headers.reserve(std::usize::MAX); // next_power_of_two overflows
+    headers.reserve(usize::MAX); // next_power_of_two overflows
 }
 
 #[test]