Bump follow-redirects and karma

Bumps [follow-redirects](https://github.com/follow-redirects/follow-redirects) to 1.15.6 and updates ancestor dependency [karma](https://github.com/karma-runner/karma). These dependencies need to be updated together.


Updates `follow-redirects` from 1.0.0 to 1.15.6
- [Release notes](https://github.com/follow-redirects/follow-redirects/releases)
- [Commits](follow-redirects/follow-redirects@v1.0.0...v1.15.6)

Updates `karma` from 2.0.0 to 6.4.3
- [Release notes](https://github.com/karma-runner/karma/releases)
- [Changelog](https://github.com/karma-runner/karma/blob/master/CHANGELOG.md)
- [Commits](karma-runner/karma@v2.0.0...v6.4.3)

---
updated-dependencies:
- dependency-name: follow-redirects
  dependency-type: indirect
- dependency-name: karma
  dependency-type: direct:development
...

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