Bump sockjs and react-scripts in /client

Bumps [sockjs](https://github.com/sockjs/sockjs-node) to 0.3.20 and updates ancestor dependency [react-scripts](https://github.com/facebook/create-react-app/tree/HEAD/packages/react-scripts). These dependencies need to be updated together.


Updates `sockjs` from 0.3.19 to 0.3.20
- [Release notes](https://github.com/sockjs/sockjs-node/releases)
- [Changelog](https://github.com/sockjs/sockjs-node/blob/v0.3.20/Changelog)
- [Commits](sockjs/sockjs-node@v0.3.19...v0.3.20)

Updates `react-scripts` from 3.1.1 to 3.4.4
- [Release notes](https://github.com/facebook/create-react-app/releases)
- [Changelog](https://github.com/facebook/create-react-app/blob/main/CHANGELOG-3.x.md)
- [Commits](https://github.com/facebook/create-react-app/commits/v3.4.4/packages/react-scripts)

---
updated-dependencies:
- dependency-name: sockjs
  dependency-type: indirect
- dependency-name: react-scripts
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>