Update bazlets to latest revision on stable-2.15

Update bazlets to use GWT version 2.8.2.

Change-Id: I84b328b1f6e1c5fad886a118ae392d530b0173e0
diff --git a/WORKSPACE b/WORKSPACE
index 76d760b..5a0dae7 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "85be3cdaa4873d0b00b5c548cecded03e018127e",
+    commit = "d9abef15db0f934bfe9adcb40b0c475807fd12bf",
     #    local_path = "/home/<user>/projects/bazlets",
 )