Bump ejs and webpack-config-single-spa-react

Removes [ejs](https://github.com/mde/ejs). It's no longer used after updating ancestor dependency [webpack-config-single-spa-react](https://github.com/single-spa/create-single-spa). These dependencies need to be updated together.


Removes `ejs`

Updates `webpack-config-single-spa-react` from 1.5.0 to 4.0.5
- [Release notes](https://github.com/single-spa/create-single-spa/releases)
- [Commits](https://github.com/single-spa/create-single-spa/compare/[email protected])

---
updated-dependencies:
- dependency-name: ejs
  dependency-type: indirect
- dependency-name: webpack-config-single-spa-react
  dependency-type: direct:development
...

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