Graph does not support std::pair as vertex type

[lxylxy123456]

To reproduce, try to compile:

#include "Graph.hpp"
int main() {
	algorithms::GraphAdjList<std::pair<int, int>> a(1);
	return 0;
}

[lxylxy123456]

This is expected, as C++ does not provide a hash function for std::pair by default.
A workaround (some code adapted from https://en.cppreference.com/w/cpp/utility/hash):

#include "Graph.hpp"

namespace std
{
    template<> struct hash<std::pair<int, int>>
    {
        std::size_t operator()(std::pair<int, int> const& s) const noexcept
        {
            std::size_t h1 = std::hash<int>{}(s.first);
            std::size_t h2 = std::hash<int>{}(s.second);
            return h1 ^ (h2 << 1); // or use boost::hash_combine
        }
    };
}

int main() {
	algorithms::GraphAdjList<std::pair<int, int>> a(1);
	// std::hash<std::pair<int, int>> a;
	return 0;
}