Bump serialize-javascript and webpack in /docs

Removes [serialize-javascript](https://github.com/yahoo/serialize-javascript). It's no longer used after updating ancestor dependency [webpack](https://github.com/webpack/webpack). These dependencies need to be updated together.


Removes `serialize-javascript`

Updates `webpack` from 4.47.0 to 5.105.4
- [Release notes](https://github.com/webpack/webpack/releases)
- [Changelog](https://github.com/webpack/webpack/blob/main/CHANGELOG.md)
- [Commits](webpack/webpack@v4.47.0...v5.105.4)

---
updated-dependencies:
- dependency-name: serialize-javascript
  dependency-version: 
  dependency-type: indirect
- dependency-name: webpack
  dependency-version: 5.105.4
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]