Upgrade bazlets to latest stable-2.16 to build with 2.16.18 API

Change-Id: I66eb15ebe3ebd3614e3a8c37ff9112098dad0f72

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 0d0631a..8bc31d3 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "9e23df10840ca3976431c842fdada58c7a51c6e3",
+    commit = "855968156ecd58d422218d6b5c9872805df9e9fc",
     #local_path = "/home/<user>/projects/bazlets",
 )