Bump http-proxy-middleware and gatsby

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


Removes `http-proxy-middleware`

Updates `gatsby` from 2.9.2 to 5.13.7
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/compare/gatsby@2.9.2...gatsby@5.13.7)

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

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