Bump ejs and generator-jhipster

Bumps [ejs](https://github.com/mde/ejs) to 3.1.10 and updates ancestor dependency [generator-jhipster](https://github.com/jhipster/generator-jhipster). These dependencies need to be updated together.


Updates `ejs` from 3.1.8 to 3.1.10
- [Release notes](https://github.com/mde/ejs/releases)
- [Commits](mde/ejs@v3.1.8...v3.1.10)

Updates `generator-jhipster` from 7.9.3 to 8.4.0
- [Release notes](https://github.com/jhipster/generator-jhipster/releases)
- [Commits](jhipster/generator-jhipster@v7.9.3...v8.4.0)

---
updated-dependencies:
- dependency-name: ejs
  dependency-type: indirect
- dependency-name: generator-jhipster
  dependency-type: direct:development
...

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