Do not ignore F401 in general

uvchik · uvchik · commit 9c040696fa4b · 2020-03-10T14:13:38.000+01:00
diff --git a/.stickler.yml b/.stickler.yml
@@ -3,7 +3,7 @@ linters:
       python: 3
       max-line-length: 79
       select: C,E,F,W,B,B950
-      ignore: E203, E501, W503, F401
+      ignore: E203, E501, W503
     black:
       config: ./pyproject.toml
       fixer: true
