group: discard the no longer necessary operator!=

src/entt/entity/group.hpp

@@ -86,11 +86,6 @@ template<typename... Lhs, typename... Rhs>
     return lhs.it == rhs.it;
 }
 
-template<typename... Lhs, typename... Rhs>
-[[nodiscard]] constexpr bool operator!=(const extended_group_iterator<Lhs...> &lhs, const extended_group_iterator<Rhs...> &rhs) noexcept {
-    return !(lhs == rhs);
-}
-
 struct group_descriptor {
     using size_type = std::size_t;
     virtual ~group_descriptor() = default;