Bump httpx[http2] from 0.17.1 to 0.18.2

Bumps [httpx[http2]](https://github.com/encode/httpx) from 0.17.1 to 0.18.2.
- [Release notes](https://github.com/encode/httpx/releases)
- [Changelog](https://github.com/encode/httpx/blob/master/CHANGELOG.md)
- [Commits](https://github.com/encode/httpx/compare/0.17.1...0.18.2

)

---
updated-dependencies:
- dependency-name: httpx[http2]
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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