Sync typeshed (#6521)

msullivan · web-flow · commit b4a939931dbd · 2019-03-06T16:05:07.000-08:00
diff --git a/mypy/typeshed b/mypy/typeshed
@@ -1 +1 @@
-Subproject commit f569957bbe047938a2d585bf58bbe96dede5301a
+Subproject commit b588d43a32e4582871d26c9396777f6f918eac36
