Use binary_t::value_type (#4805)

include/nlohmann/detail/input/binary_reader.hpp

@@ -2944,7 +2944,7 @@ class binary_reader
                 success = false;
                 break;
             }
-            result.push_back(static_cast<std::uint8_t>(current));
+            result.push_back(static_cast<typename binary_t::value_type>(current));
         }
         return success;
     }