Bump ansi-html and webpack-dev-server in /demo

Removes [ansi-html](https://github.com/Tjatse/ansi-html). It's no longer used after updating ancestor dependency [webpack-dev-server](https://github.com/webpack/webpack-dev-server). These dependencies need to be updated together.


Removes `ansi-html`

Updates `webpack-dev-server` from 3.11.2 to 3.11.3
- [Release notes](https://github.com/webpack/webpack-dev-server/releases)
- [Changelog](https://github.com/webpack/webpack-dev-server/blob/v3.11.3/CHANGELOG.md)
- [Commits](webpack/webpack-dev-server@v3.11.2...v3.11.3)

---
updated-dependencies:
- dependency-name: ansi-html
  dependency-type: indirect
- dependency-name: webpack-dev-server
  dependency-type: direct:development
...

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

Author: dependabot[bot]