Method release

include/stdexec/__detail/__associate.hpp:123–127

      }

      std::pair<__assoc_t, __sender_ref> release() && noexcept
      {
        __sender_ref __u(__assoc_ ? std::addressof(__sndr_) : nullptr);
        return {std::move(__assoc_), std::move(__u)};
      }

     private:
      explicit __associate_data(std::pair<__assoc_t, __sender_ref> __parts)