fix: httpx v0.28.0 proxies bug

[Aries-ckt]

Close #2173

Description

httpx v0.28.0 proxies bug
Realease note of httpx v0.28.0

How Has This Been Tested?

import asyncio

from dbgpt.core import ModelRequest
from dbgpt.model.proxy.llms.chatgpt import OpenAILLMClient  # type: ignore


async def main():
    client = OpenAILLMClient(model_alias="gpt-4o-mini")
    response = await client.generate(ModelRequest._build("gpt-4o-mini", "Hi!"))
    print(response)


asyncio.run(main())

Snapshots:

Include snapshots for easier review.

Checklist:

• My code follows the style guidelines of this project
• I have already rebased the commits and make the commit message conform to the project standard.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• Any dependent changes have been merged and published in downstream modules

[yihong0618]

why not choose to fixed httpx version?

[Appointat]

@Aries-ckt hi. Have you checked the dependencies of DB-GPT? Just to avoid the unnecessary version conflicts.

[fangyinc]

why not choose to fixed httpx version?

Fixed versions may conflict with other packages~

[fangyinc]

LGTM.

[csunny]

r+