Bump httpx from 0.21.1 to 0.21.2 (#70)

Bumps [httpx](https://github.com/encode/httpx) from 0.21.1 to 0.21.2.
- [Release notes](https://github.com/encode/httpx/releases)
- [Changelog](https://github.com/encode/httpx/blob/master/CHANGELOG.md)
- [Commits](encode/httpx@0.21.1...0.21.2)

---
updated-dependencies:
- dependency-name: httpx
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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