Bump httpx from 0.27.2 to 0.28.1 in the dev-deps group

Bumps the dev-deps group with 1 update: [httpx](https://github.com/encode/httpx).


Updates `httpx` from 0.27.2 to 0.28.1
- [Release notes](https://github.com/encode/httpx/releases)
- [Changelog](https://github.com/encode/httpx/blob/master/CHANGELOG.md)
- [Commits](encode/httpx@0.27.2...0.28.1)

---
updated-dependencies:
- dependency-name: httpx
  dependency-type: direct:development
  update-type: version-update:semver-minor
  dependency-group: dev-deps
...

Signed-off-by: dependabot[bot] <[email protected]>