Update httpx requirement from ~=0.27.0 to ~=0.28.0 in /package (#2216)

Updates the requirements on [httpx](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
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package/test_requirements.txt

@@ -18,7 +18,7 @@ ruff==0.7.0
 sqlalchemy-stubs~=0.4
 strawberry-graphql[cli]>=0.99.0, <1.0
 trufflehog~=2.2
-httpx~=0.27.0
+httpx~=0.28.0
 pathspec>=0.12.1
 
 # mypy