Update httpx requirement from 0.27.2 to 0.28.0

Updates the requirements on [httpx](https://github.com/encode/httpx) to permit the latest version.
- [Release notes](https://github.com/encode/httpx/releases)
- [Changelog](https://github.com/encode/httpx/blob/master/CHANGELOG.md)
- [Commits](encode/httpx@0.27.2...0.28.0)

---
updated-dependencies:
- dependency-name: httpx
  dependency-type: direct:development
...

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

pyproject.toml

@@ -14,7 +14,7 @@ uvicorn = "0.32.0"
 pytest = "8.3.3"
 pytest-cov = "^6.0.0"
 ruff = "^0.8.1"
-httpx = "0.27.2"
+httpx = "0.28.0"
 
 [tool.pytest.ini_options]
 testpaths = ["tests",]