Bump httpx from 0.27.2 to 0.28.0

Bumps [httpx](https://github.com/encode/httpx) from 0.27.2 to 0.28.0.
- [Release notes](https://github.com/encode/httpx/releases)
- [Changelog](https://github.com/encode/httpx/blob/master/CHANGELOG.md)
- [Commits](https://github.com/encode/httpx/compare/0.27.2...0.28.0

)

---
updated-dependencies:
- dependency-name: httpx
  dependency-type: direct:production
  update-type: version-update:semver-minor
...
Signed-off-by: dependabot[bot] <support@github.com>

Pipfile

@@ -9,7 +9,7 @@ pymarc = "==5.2.3"
 uvicorn = {version = "==0.32.0", extras = ["standard"]}
 xmltodict = "==0.14.2"
 zeep = {version = "==4.3.1", extras = ["async"]}
-httpx = "==0.27.2"
+httpx = "==0.28.0"
 
 [dev-packages]
 pre-commit = "==4.0.1"