Error compiling with VS 2013

[Alberto Garcia Illera]

Just including cpptoml.h compiles fine with VS2017 and VS2015 but not with VS2013 which is the one that I need for compatibility reasons.
Can you please fix that?

1>------ Build started: Project: Project2, Configuration: Debug x64 ------
1>Source.cpp
1>c:\users\d\source\repos\project2\project2\cpptoml.h(63): error C2797: 'cpptoml::option<std::vector<std::shared_ptr<cpptoml::array>,std::allocator<_Ty>>>::value_': list initialization inside member initializer list or non-static data member initializer is not implemented
1>        with
1>        [
1>            _Ty=std::shared_ptr<cpptoml::array>
1>        ]
1>        c:\users\default.laptop-bgosj7n3\source\repos\project2\project2\cpptoml.h(62) : while compiling class template member function 'cpptoml::option<std::vector<std::shared_ptr<cpptoml::array>,std::allocator<_Ty>>>::option(T)'
1>        with
1>        [
1>            _Ty=std::shared_ptr<cpptoml::array>
1>,            T=std::vector<std::shared_ptr<cpptoml::array>,std::allocator<std::shared_ptr<cpptoml::array>>>
1>        ]
1>        c:\users\default.laptop-bgosj7n3\source\repos\project2\project2\cpptoml.h(893) : see reference to function template instantiation 'cpptoml::option<std::vector<std::shared_ptr<cpptoml::array>,std::allocator<_Ty>>>::option(T)' being compiled
1>        with
1>        [
1>            _Ty=std::shared_ptr<cpptoml::array>
1>,            T=std::vector<std::shared_ptr<cpptoml::array>,std::allocator<std::shared_ptr<cpptoml::array>>>
1>        ]
1>        c:\users\default.laptop-bgosj7n3\source\repos\project2\project2\cpptoml.h(894) : see reference to class template instantiation 'cpptoml::option<std::vector<std::shared_ptr<cpptoml::array>,std::allocator<_Ty>>>' being compiled
1>        with
1>        [
1>            _Ty=std::shared_ptr<cpptoml::array>
1>        ]
1>Done building project "Project2.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Thanks and regards