Bump express and lightning

Bumps [express](https://github.com/expressjs/express) to 4.18.1 and updates ancestor dependency [lightning](https://github.com/alexbosworth/lightning). These dependencies need to be updated together.


Updates `express` from 4.17.2 to 4.18.1
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/master/History.md)
- [Commits](expressjs/express@4.17.2...4.18.1)

Updates `lightning` from 5.4.0 to 5.21.2
- [Release notes](https://github.com/alexbosworth/lightning/releases)
- [Changelog](https://github.com/alexbosworth/lightning/blob/master/CHANGELOG.md)
- [Commits](https://github.com/alexbosworth/lightning/commits)

---
updated-dependencies:
- dependency-name: express
  dependency-type: indirect
- dependency-name: lightning
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>