Added template parameter to convert struct to be able to use std::enable_if.

include/yaml-cpp/node/convert.h

@@ -23,7 +23,7 @@
 namespace YAML {
 class Binary;
 struct _Null;
-template <typename T>
+template <typename T, typename Enable>
 struct convert;
 }  // namespace YAML
 

include/yaml-cpp/node/node.h

@@ -138,7 +138,7 @@ YAML_CPP_API bool operator==(const Node& lhs, const Node& rhs);
 
 YAML_CPP_API Node Clone(const Node& node);
 
-template <typename T>
+template <typename T, typename Enable = void>
 struct convert;
 }