fix clippy lint

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

vm/src/stdlib/winreg.rs

@@ -98,7 +98,7 @@ mod winreg {
 
         #[pymethod(magic)]
         fn bool(&self) -> bool {
-            self.key().raw_handle() != core::ptr::null_mut()
+            !self.key().raw_handle().is_null()
         }
         #[pymethod(magic)]
         fn enter(zelf: PyRef<Self>) -> PyRef<Self> {