Update prezto

diff --git a/prezto b/prezto
index b97f6a272cf409cd88b84e3845e196f3ea4f6525..e21d3dce9edebab44ebc876fd32ed0cf22cb8b55 160000 (submodule)
--- a/prezto
+++ b/prezto
@@ -1 +1 @@
-Subproject commit b97f6a272cf409cd88b84e3845e196f3ea4f6525
+Subproject commit e21d3dce9edebab44ebc876fd32ed0cf22cb8b55