Merge pull request #840 from pre-commit/all-repos_autofix_no-implicit-optional

remove no_implicit_optional
diff --git a/setup.cfg b/setup.cfg
index d4658e2..30688d9 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -75,7 +75,6 @@
 disallow_any_generics = true
 disallow_incomplete_defs = true
 disallow_untyped_defs = true
-no_implicit_optional = true
 warn_redundant_casts = true
 warn_unused_ignores = true