build(deps): bump httpx from 0.25.1 to 0.28.1

Bumps [httpx](https://github.com/encode/httpx) from 0.25.1 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@0.25.1...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]

requirements.txt

@@ -7,7 +7,7 @@ qdrant-client==1.15.1
 openai==1.3.5
 anthropic==0.7.2
 tiktoken==0.5.2
-httpx==0.25.1
+httpx==0.28.1
 sentence-transformers==2.2.2
 python-dotenv==1.0.0
 structlog==23.2.0