Fix build failure on C++20

Author: mikee47

src/include/FlashString/Object.hpp

@@ -103,10 +103,13 @@ template <class ObjectType, typename ElementType> class Object : public ObjectBa
 	using DataPtrType = const ElementType*;
 	using Iterator = ObjectIterator<ObjectType, ElementType>;
 
+// This is precautionary to prevent misuse. No known fix for C++20.
+#if __cplusplus < 202002L
 	Object(const Object&) = delete;
 	Object(const Object&&) = delete;
 	Object& operator=(const Object&) = delete;
 	Object& operator=(const Object&&) = delete;
+#endif
 
 	Iterator begin() const
 	{