Import problem

首先，使用文档中指定的 Python 3.9 Docker 镜像和 Firebase SDK 版本，复现从 source/tests/conftest.py 执行的 import。跟踪依赖项通过 firebase_admin.auth、httplib2 和 pyparsing 的导入过程，以确定不兼容之处；当 import 在没有报告的 AttributeError 的情况下完成时，即表示完成。

• Operating System version: docker image python:3.9 (debian bullseye)
• Firebase SDK version: firebase_admin-5.0.3
• Firebase Product: auth
• Python version: 3.9
• Pip version: 21.2.4

Steps to reproduce:

Hello everyone!
I've got some import problem while importing auth module today:

source/tests/conftest.py:7: in <module>
    import firebase_admin.auth
/usr/local/lib/python3.9/site-packages/firebase_admin/auth.py:22: in <module>
    from firebase_admin import _auth_client
/usr/local/lib/python3.9/site-packages/firebase_admin/_auth_client.py:20: in <module>
    from firebase_admin import _auth_providers
/usr/local/lib/python3.9/site-packages/firebase_admin/_auth_providers.py:21: in <module>
    from firebase_admin import _auth_utils
/usr/local/lib/python3.9/site-packages/firebase_admin/_auth_utils.py:23: in <module>
    from firebase_admin import _utils
/usr/local/lib/python3.9/site-packages/firebase_admin/_utils.py:23: in <module>
    import httplib2
/usr/local/lib/python3.9/site-packages/httplib2/__init__.py:52: in <module>
    from . import auth
/usr/local/lib/python3.9/site-packages/httplib2/auth.py:20: in <module>
    auth_param_name = token.copy().setName("auth-param-name").addParseAction(pp.downcaseTokens)
E   AttributeError: module 'pyparsing' has no attribute 'downcaseTokens'

Relevant Code:

import firebase_admin.auth