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

Change-Id: Iebdb901ca460a367d9729f2bb4975897a8dcb714
diff --git a/WORKSPACE b/WORKSPACE
index bf95d57..6d68b8c 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "88570121c377a8a94c76915566114bf02113a7d9",
+    commit = "087da1f6ca119ad5c4bc443926426ddf44dcde3a",
     #local_path = "/home/<user>/projects/bazlets",
 )