Adapted get_mut_unchecked to not to use removed unwrap_unchecked

src/imp_std.rs

@@ -112,7 +112,7 @@ impl<T> OnceCell<T> {
     pub(crate) unsafe fn get_mut_unchecked(&mut self) -> &mut T {
         debug_assert!(self.is_initialized());
         let slot = &mut *self.value.get();
-        crate::unwrap_unchecked(slot.as_mut())
+        slot.as_mut().unwrap_unchecked()
     }
 
     /// Gets the mutable reference to the underlying value.