Upgrade bazlets to latest stable-3.4 to build with 3.4.0 API

Change-Id: Id6a4a8e7a46b8a51222e6ef8c437a1f11ed7bdb2
diff --git a/WORKSPACE b/WORKSPACE
index df08867..e1bee62 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "10e78cc706760ff24cbc67ba527f9a8e4134d66f"
+    commit = "7ff4605f48db148197675a0d2ea41ee07cb72fd3"
     #local_path = "/home/<user>/projects/bazlets",
 )