chore(deps)(deps): bump httpx from 0.25.2 to 0.28.1

Bumps [httpx](https://github.com/encode/httpx) from 0.25.2 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@0.25.2...0.28.1)

---
updated-dependencies:
- dependency-name: httpx
  dependency-version: 0.28.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

gateway_poc/requirements.txt

@@ -1,6 +1,6 @@
 fastapi==0.104.1
 uvicorn[standard]==0.24.0
-httpx==0.25.2
+httpx==0.28.1
 redis==5.0.1
 pydantic==2.5.0
 python-multipart==0.0.6