Bump ejs and react-scripts in /app

Bumps [ejs](https://github.com/mde/ejs) to 3.1.8 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 `ejs` from 2.7.4 to 3.1.8
- [Release notes](https://github.com/mde/ejs/releases)
- [Changelog](https://github.com/mde/ejs/blob/main/CHANGELOG.md)
- [Commits](mde/ejs@v2.7.4...v3.1.8)

Updates `react-scripts` from 4.0.3 to 5.0.1
- [Release notes](https://github.com/facebook/create-react-app/releases)
- [Changelog](https://github.com/facebook/create-react-app/blob/main/CHANGELOG-4.x.md)
- [Commits](https://github.com/facebook/create-react-app/commits/[email protected]/packages/react-scripts)

---
updated-dependencies:
- dependency-name: ejs
  dependency-type: indirect
- dependency-name: react-scripts
  dependency-type: direct:production
...

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