chore(deps): update httpx requirement from >=0.27 to >=0.28.1

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...0.28.1)

---
updated-dependencies:
- dependency-name: httpx
  dependency-version: 0.28.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pyproject.toml

@@ -14,7 +14,7 @@ dependencies = [
   "azure-mgmt-subscription>=3.1",
   "azure-mgmt-consumption>=10.0",
   "azure-eventgrid>=4.16",
-  "httpx>=0.27",
+  "httpx>=0.28.1",
 ]
 
 [project.optional-dependencies]