Support react 19

[rotem1850]

The latest version to react-pivottable doesnt support React 19.
I get alot of "Error: t.findDOMNode is not a function" when using it

[Danchoys]

#183

This PR should address the problem

[korsbakken]

Hi. Some questions about this one. I am facing similar issues, with error messages about ReactDOM.findDomNode and ReactDOM.hasOwnProperty "is not a function". They do seem to go back to react-draggable, as mentioned in PR #183. But:

1. I am getting the same errors in React 18.2 as well, not just in React 19.
2. PR fix: Make react-pivottable compatible with React 19 #183 might address the problem, but it was closed without being merged. Was that intentional? And if so, is there something wrong with the code in the PR?

Thanks!