Bump http-proxy-middleware and netlify-cli (#105)

Removes [http-proxy-middleware](https://github.com/chimurai/http-proxy-middleware). It's no longer used after updating ancestor dependency [netlify-cli](https://github.com/netlify/cli). These dependencies need to be updated together.


Removes `http-proxy-middleware`

Updates `netlify-cli` from 18.1.0 to 20.1.1
- [Release notes](https://github.com/netlify/cli/releases)
- [Changelog](https://github.com/netlify/cli/blob/main/CHANGELOG.md)
- [Commits](netlify/cli@v18.1.0...v20.1.1)

---
updated-dependencies:
- dependency-name: http-proxy-middleware
  dependency-version: 
  dependency-type: indirect
- dependency-name: netlify-cli
  dependency-version: 20.1.1
  dependency-type: direct:development
...

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Author: dependabot[bot]