Bug: `PasswordHash` breaks Alembic autogenerate when backend is required

[renjianguo666]

Description

Hi! I ran into an issue when using the built-in PasswordHash type with Alembic autogenerate.

At migration runtime this fails with:

URL to code causing the issue

No response

MCVE

# Your MCVE code here

Steps to reproduce

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Screenshots

"In the format of: ![SCREENSHOT_DESCRIPTION](SCREENSHOT_LINK.png)"

Logs

Package Version

v1.6.3

Platform

• Linux
• Mac
• Windows
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