Fix StrictMode warning

[aralroca]

Using React.StrictMode is throwing this warning:

findDOMNode is deprecated in StrictMode. findDOMNode was passed 
an instance of ReactSwipe which is inside StrictMode. Instead, add a 
ref directly to the element you want to reference.

Should be fixed to allow Concurrent mode in the future React releases.

In order to fix it: The ref should be under React.createRef

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.