Correct casting to pointer instead of reference

Author: filipsajdak

include/cpp2util.h

@@ -539,7 +539,7 @@ auto is( X const& x ) -> bool {
 template< typename C, typename X >
  requires (std::is_base_of_v<X, C> && !std::is_same_v<C,X>)
 auto is( X const* x ) -> bool {
- return dynamic_cast<C const&>(x) != nullptr;
+ return dynamic_cast<C const*>(x) != nullptr;
 }
 
 template< typename C, typename X >