Upgrade bazlets to latest master to build with 3.1.0 API

Change-Id: Iafe58d8b32df85e2ca8f1f1b540739a5b6d3e4f9
diff --git a/WORKSPACE b/WORKSPACE
index 04fed37..3f8b6c4 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",
 )