Remove unused ReactDOM (#51)

Author: Joel Denning

src/react-mf-planets.js

@@ -1,12 +1,10 @@
 import React from "react";
-import ReactDOM from "react-dom";
 import ReactDOMClient from "react-dom/client";
 import singleSpaReact from "single-spa-react";
 import Root from "./root.component";
 
 const lifecycles = singleSpaReact({
   React,
-  ReactDOM,
   ReactDOMClient,
   rootComponent: Root,
   errorBoundary(err, info, props) {