1.7.7: sphinx warnings

**Describe the bug**
Looks like lates sphinx shows a lot of warnings on generate documentation.

**Expected behavior**
Sphinx should not show warnings.

**To Reproduce**
`python setup.py build_sphinx -b man`

**Versions.**
 - OS: Linux x86/64
 - Python: 3.8.13
 - Alembic: 1.7.7
 - SQLAlchemy:  1.4.35
 - Database: N/A
 - DBAPI: N/A