[pre-commit.ci] pre-commit autoupdate

Author: pre-commit-ci[bot]

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 exclude: doc/en/example/py2py3/test_py2.py
 repos:
--   repo: https://github.com/python/black
+-   repo: https://github.com/psf/black
     rev: 20.8b1
     hooks:
     -   id: black