Upgrade bazlets to latest master to build with 3.1.4 API

Change-Id: I32daaa0106bd23a9b6ec1f06e9d4be8db7f26cfb

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 9f64353..5d2a5aa 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "2add9fecf8bec8634bddf354815bd0fa93f58dd5",
+    commit = "cd715d269734e7bb0aa2fc4a01d2d2e279631cc7",
     #local_path = "/home/<user>/projects/bazlets",
 )