chore(deps-dev): update pytest requirement in /packages/http/httpx

Updates the requirements on [pytest](https://github.com/pytest-dev/pytest) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@8.3.2...9.1.0)

---
updated-dependencies:
- dependency-name: pytest
  dependency-version: 9.1.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]

packages/http/httpx/requirements-dev.txt

@@ -4,6 +4,6 @@ yapf>=0.40.2,<0.44.0
 isort>=8.0.1,<9.0.0
 pylint>=3.2.7,<5.0.0
 mypy>=1.11.2,<3.0.0
-pytest>=8.3.2,<10.0.0
+pytest>=9.1.0,<10.0.0
 pytest-asyncio>=1.4.0,<1.5
 pytest-mock>=3.14.0,<4.0.0