Update bazlets to latest version to fix py3 support

Change-Id: I3d5150649ab8a1790d1da52f71f6c2db862babaa

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 4043bff..2ecbbb3 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//tools:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "8c91ef43828699c7ed33976897991a427dcfe04b",
+    commit = "6dad39cdb50b83afa7fe57783c10b272305f97ba",
     # local_path = "/home/<user>/projects/bazlets",
 )