Made code more idiomatic (::core -> core and ::std -> std)

Author: ChaiTRex

library/core/tests/num/int_sqrt.rs

@@ -202,7 +202,7 @@ macro_rules! signed_check {
                     "`({negative_n}).checked_isqrt()` should be `None`, as {negative_n} is negative.",
                 );
 
-                ::std::panic::catch_unwind(::core::panic::AssertUnwindSafe(|| (-n).isqrt())).expect_err(
+                std::panic::catch_unwind(core::panic::AssertUnwindSafe(|| (-n).isqrt())).expect_err(
                     &format!("`({negative_n}).isqrt()` should have panicked, as {negative_n} is negative.")
                 );
             }
@@ -222,7 +222,7 @@ macro_rules! unsigned_check {
             if n > 0 {
                 assert_eq!(
                     n.isqrt(),
-                    ::core::num::NonZero::<$T>::new(n)
+                    core::num::NonZero::<$T>::new(n)
                         .expect(
                             "Was not able to create a new `NonZero` value from a nonzero number."
                         )