Bump form-data, start-server-and-test and web-ext

Bumps [form-data](https://github.com/form-data/form-data) to 4.0.4 and updates ancestor dependencies [form-data](https://github.com/form-data/form-data), [start-server-and-test](https://github.com/bahmutov/start-server-and-test) and [web-ext](https://github.com/mozilla/web-ext). These dependencies need to be updated together.


Updates `form-data` from 2.3.3 to 4.0.4
- [Release notes](https://github.com/form-data/form-data/releases)
- [Changelog](https://github.com/form-data/form-data/blob/master/CHANGELOG.md)
- [Commits](https://github.com/form-data/form-data/commits/v4.0.4)

Updates `start-server-and-test` from 1.11.0 to 1.15.4
- [Release notes](https://github.com/bahmutov/start-server-and-test/releases)
- [Commits](bahmutov/start-server-and-test@v1.11.0...v1.15.4)

Updates `web-ext` from 7.12.0 to 8.9.0
- [Release notes](https://github.com/mozilla/web-ext/releases)
- [Commits](mozilla/web-ext@7.12.0...8.9.0)

---
updated-dependencies:
- dependency-name: form-data
  dependency-version: 4.0.4
  dependency-type: indirect
- dependency-name: start-server-and-test
  dependency-version: 1.15.4
  dependency-type: direct:development
- dependency-name: web-ext
  dependency-version: 8.9.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]