Upgrade bazlets to latest master to build with 3.1.0-rc1 API

Change-Id: I68c05bdb8fcf05a6ff34367414eaf661e457ab6c
diff --git a/WORKSPACE b/WORKSPACE
index f27c199..74b36a0 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "acfed42f6ad6863b1906da240b564b6f714e6b75",
+    commit = "97e83629a68dedda29125657a0a0a8cb21094de1",
     #local_path = "/home/<user>/projects/bazlets",
 )