chore(deps-dev): Bump next from 9.3.6 to 9.4.0

Bumps [next](https://github.com/zeit/next.js) from 9.3.6 to 9.4.0.
- [Release notes](https://github.com/zeit/next.js/releases)
- [Commits](vercel/next.js@v9.3.6...v9.4.0)

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