Bump json5, ava and webpack in /js (#11)

Removes [json5](https://github.com/json5/json5). It's no longer used after updating ancestor dependencies [json5](https://github.com/json5/json5), [ava](https://github.com/avajs/ava) and [webpack](https://github.com/webpack/webpack). These dependencies need to be updated together.


Removes `json5`

Updates `ava` from 0.19.1 to 6.1.2
- [Release notes](https://github.com/avajs/ava/releases)
- [Commits](avajs/ava@v0.19.1...v6.1.2)

Updates `webpack` from 3.0.0 to 5.91.0
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](webpack/webpack@v3.0.0...v5.91.0)

---
updated-dependencies:
- dependency-name: json5
  dependency-type: indirect
- dependency-name: ava
  dependency-type: direct:development
- dependency-name: webpack
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]