deps: update httpx requirement from <0.28,>=0.27 to >=0.27,<0.29

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@0.27.0...0.28.1)

---
updated-dependencies:
- dependency-name: httpx
  dependency-version: 0.28.1
  dependency-type: direct:development
...

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

Author: dependabot[bot]

pyproject.toml

@@ -38,7 +38,7 @@ dependencies = [
 dev = [
     "pytest>=8.2,<9.0",
     "pytest-asyncio>=0.23,<0.24",
-    "httpx>=0.27,<0.28",
+    "httpx>=0.27,<0.29",
     "black>=24.4,<25.0",
     "isort>=5.13,<6.0",
     "coverage[toml]>=7.5,<8.0",