Revert "Bump react-scripts from 3.4.4 to 4.0.1"

This reverts commit f825ea1.

The upgrade to react-scripts includes an upgrade to jest-environment-jsdom which
introduces a regression with firebase related tests detailed here:
  https://stackoverflow.com/q/61914567
  jestjs/jest#7780
  firebase/firebase-js-sdk#3096

It's easier to hold back on the react-scripts upgrade for now.

package.json

@@ -18,7 +18,7 @@
     "react": "^16.14.0",
     "react-dom": "^16.14.0",
     "react-router-dom": "^5.2.0",
-    "react-scripts": "4.0.1",
+    "react-scripts": "3.4.4",
     "semantic-ui-react": "^2.0.1",
     "typescript": "~4.0.5",
     "uuid": "^8.3.2"