Specialize Attributes size() function for EnumString struct

include/aidge/utils/Attributes.hpp

@@ -12,7 +12,6 @@
 #ifndef AIDGE_CORE_UTILS_ATTRIBUTES_H_
 #define AIDGE_CORE_UTILS_ATTRIBUTES_H_
 
-#include <vector>
 #include <string>
 #include <set>
 
@@ -36,6 +35,9 @@ namespace Aidge {
 template<class T, std::size_t N>
 constexpr std::size_t size(T (&)[N]) { return N; }
 
+template<std::size_t N>
+constexpr std::size_t size(const char* const (&)[N]) { return N; }
+
 /* This abstract class allows to avoid binding Attributes.
 *  Otherwise we would need to bind every template possible of Attributes.
 *  Every operators can access the methods of this class by inheriting from