Bump httpx from 0.21.3 to 0.22.0

Bumps [httpx](https://github.com/encode/httpx) from 0.21.3 to 0.22.0.
- [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/0.21.3...0.22.0)

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

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

pyproject.toml

@@ -19,7 +19,7 @@ Changelog = "https://github.com/andrewthetechie/py-healthchecks.io/releases"
 python = "^3.7"
 click = "^8.0.1"
 pydantic = "^1.8.2"
-httpx = "^0.21.1"
+httpx = ">=0.21.1,<0.23.0"
 croniter = "^1.1.0"
 pytz = "^2021.3"