Update dependency httpx to ^0.28.0

| datasource | package | from   | to     |
| ---------- | ------- | ------ | ------ |
| pypi       | httpx   | 0.27.0 | 0.28.1 |

Author: renovate[bot]

poetry.lock

@@ -13,7 +13,7 @@ uvicorn = { extras = ["standard"], version = "^0.30.1" }
 motor = "3.5.1"
 python-dotenv = "^1.0.1"
 pyjwt = "^2.8.0"
-httpx = "^0.27.0"
+httpx = "^0.28.0"
 pydantic = "^1.10.17"
 spectree = "^1.2.10"
 deepmerge = "^1.1.1"