Upgrade bazlets to latest stable-3.1 to build with 3.1.12 API

Change-Id: I05370daf2d917b5ecf778327f174f6612106716b

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 9b24a27..56b744a 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "20079f696c22c733053077b13c0dc6d9902e6b8e",
+    commit = "87fd5f0d0a89d01df13deaf2d21a4bdb3bc03cfd",
     #local_path = "/home/<user>/projects/bazlets",
 )