Autoflake upgrade (#159)

* Use official autoflake mirror

* Use official autoflake repo and upgrade

Author: benjaoming

pre-commit-config.yaml

@@ -37,8 +37,8 @@ repos:
     - id: mixed-line-ending
       args: ['--fix=lf']
 
-- repo: https://github.com/humitos/mirrors-autoflake.git
-  rev: v1.1
+- repo: https://github.com/PyCQA/autoflake
+  rev: v1.7.7
   hooks:
     - id: autoflake
       args: ['--in-place', '--remove-all-unused-imports', '--remove-unused-variable']