Bump govspeak from 6.8.3 to 8.3.4

Bumps [govspeak](https://github.com/alphagov/govspeak) from 6.8.3 to 8.3.4.
- [Changelog](https://github.com/alphagov/govspeak/blob/main/CHANGELOG.md)
- [Commits](alphagov/govspeak@v6.8.3...v8.3.4)

---
updated-dependencies:
- dependency-name: govspeak
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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