bug:无法发起x-www-form-urlencoded 请求

[clarencehua]

Pre-submission checklist:

• I have searched the relevant information in the existing list of Issues.
• I have searched the developer documentation for that information: https://www.justauth.cn
• I have read the relevant Q&A: https://www.justauth.cn

Issue description

Environment

• JustAuth version(e.g. 1.15.1):

Minimal test code / Steps to reproduce the issue

What's the actual result? (including assertion message & call stack if applicable)

Be sure to provide a complete and detailed exception stack.

What's the expected result?

[zhangyd-c]

请提供具体报错信息