chore(deps): update httpx[http2] requirement from ~=0.27.0 to ~=0.28.0

Updates the requirements on [httpx[http2]](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...0.28.0)

---
updated-dependencies:
- dependency-name: httpx[http2]
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

pyproject.toml

@@ -12,7 +12,7 @@ dependencies = [
     "promplate-trace[langfuse,langsmith]==0.3.0dev5",
     "python-box~=7.2.0",
     "pydantic-settings~=2.6.0",
-    "httpx[http2]~=0.27.0",
+    "httpx[http2]~=0.28.0",
     "promptools[stream,validation]~=0.1.3.3",
     "fake-useragent~=1.5.1",
     "html2text~=2024.2.26",