Bump httpx from 0.27.2 to 0.28.1 in /tests/UDKTests

Bumps [httpx](https://github.com/encode/httpx) from 0.27.2 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@0.27.2...0.28.1)

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

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

tests/UDKTests/requirements.txt

@@ -1,4 +1,4 @@
-httpx==0.27.2
+httpx==0.28.1
 psutil==6.0.0
 py7zr==0.22.0
 tqdm==4.66.5