Bump serialize-javascript and webpack

Bumps [serialize-javascript](https://github.com/yahoo/serialize-javascript) to 4.0.0 and updates ancestor dependency [webpack](https://github.com/webpack/webpack). These dependencies need to be updated together.


Updates `serialize-javascript` from 1.7.0 to 4.0.0
- [Release notes](https://github.com/yahoo/serialize-javascript/releases)
- [Commits](yahoo/serialize-javascript@v1.7.0...v4.0.0)

Updates `webpack` from 4.20.2 to 4.47.0
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](webpack/webpack@v4.20.2...v4.47.0)

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

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