clone function set attribute invalid[bug]

[cangshudada]

Describe the bug
When I clone the first DOM, the new attributes returned by the clone method are invalid, and will be effective when multiple identical DOMs are cloned

This BUG also exists in the official example！

Client: Chrome browser

package.json
"react-sortablejs": "^2.0.11"

[cangshudada]

I have solved it in this PR #173