Upgrade bazlets to latest stable-2.15 to build with 2.15.6 API

Change-Id: I63117b6e49bc7cda62c9316e3d97dcc21a8f51b1

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 7442807..67f51a2 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "6d3fd710ea4ca44805bb8c858d72b53bd3a500f3",
+    commit = "087da1f6ca119ad5c4bc443926426ddf44dcde3a",
     #local_path = "/home/<user>/projects/bazlets",
 )