Sync typeshed to the version that has TypeGuard

gvanrossum · gvanrossum · commit 708f2e538ed3 · 2020-12-30T14:33:04.000-08:00
diff --git a/mypy/typeshed b/mypy/typeshed
@@ -1 +1 @@
-Subproject commit b3974b904fbe76b2e42e32dbf4bc53b7ea5c5aab
+Subproject commit dcaea8bf06191d00c51a73fd932af09097cf208a
