doccano-client does not support urllib3 2.0.0

How to reproduce the behaviour
---------
I use poetry in my project. I just added doccano-client ("poetry add doccano-client"). My pyproject.toml looks like

```
[tool.poetry]
name = "poetry-demo"
version = "0.1.0"
description = ""
authors = ["CHARLES-HENRI PRAT"]
readme = "README.md"

[tool.poetry.dependencies]
python = "^3.10"
doccano-client = "^1.2.8"

[build-system]
requires = ["poetry-core"]
build-backend = "poetry.core.masonry.api"

```

And then when I just run `python -c "import requests_toolbelt"` I get this error
ImportError: cannot import name 'appengine' from 'urllib3.contrib' (/Users/charlesprat/RepoGit/poetry-demo/.venv/lib/python3.10/site-packages/urllib3/contrib/__init__.py)

Quick Fix
---------
If I put a constraint on urllib3 version (poetry add urllib3@1.26), the error disappears.

Your Environment
---------

* Operating System: Mac OS 14.1.1 (23B81)
* Python Version: 3.10
* Package Version: 1.2.8