Upgrade bazlets to latest master to build with 3.1.0 API

Change-Id: Idcc84ad621801b0488874fdab7e6e39d5661f4d0

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 18afd76..37dd691 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "3c5c68992ede5e2b6722abf4da03b034b57c8e89",
+    commit = "5f7ca2e226195c2de6eece2c160a9a7690dc7be8",
     #local_path = "/home/<user>/projects/bazlets",
 )