added uint32_t support

Author: stephenberry

include/argz/argz.hpp

@@ -25,7 +25,7 @@ namespace argz
    template <class T>
    using ref = std::reference_wrapper<T>;
 
-   using var = std::variant<ref<bool>, ref<int32_t>, ref<int64_t>, ref<uint64_t>, ref<std::string>>;
+   using var = std::variant<ref<bool>, ref<int32_t>, ref<uint32_t>, ref<int64_t>, ref<uint64_t>, ref<std::string>>;
 
    struct ids_t final {
       std::string_view id{};