Bump http-proxy-middleware from 2.0.6 to 2.0.7 in /tests/builds/webpack

Bumps [http-proxy-middleware](https://github.com/chimurai/http-proxy-middleware) from 2.0.6 to 2.0.7.
- [Release notes](https://github.com/chimurai/http-proxy-middleware/releases)
- [Changelog](https://github.com/chimurai/http-proxy-middleware/blob/v2.0.7/CHANGELOG.md)
- [Commits](chimurai/http-proxy-middleware@v2.0.6...v2.0.7)

---
updated-dependencies:
- dependency-name: http-proxy-middleware
  dependency-type: indirect
...

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