Migrate to httpx2

### Confirm this is a Python library issue and not an underlying Cloudflare API issue.

- [x] This is an issue with the Python library

### Describe the bug

This project currently depends on httpx, which is no longer maintained. Given that situation, it should be migrated away to a maintained http library. One such option is `httpx2` (https://github.com/pydantic/httpx2), which seems to be the accepted community fork of httpx, specially given it's maintained by pydantic. This is even more true, when the author of `httpxyz` (a previous fork) [blesses](https://tildeweb.nl/~michiel/httpx2.html) this new package.

Note that Sentry, already added support for this package in https://github.com/getsentry/sentry-python/issues/6448.

### To Reproduce

Check the project dependencies

### Code snippets

```Python

```

### OS

any

### Python version

any

### Library version

5.x

首先檢查專案相依性，找出 httpx 在哪裡宣告，以及它在 Python 程式庫中如何使用。將這些參照遷移至受維護的 httpx2 套件，然後執行程式庫現有的測試套件，以確認相依性變更在所有受支援的使用方式中都能正常運作。

由索引模型根據 Issue 內容生成。