Update bazlets to latest revision on stable-2.15

- Build with 2.15.1 API
- Use bazel-cache instead of buck-cache

Change-Id: I368eadf5b349b63a58a10101b6e336800ab8c8bd
diff --git a/WORKSPACE b/WORKSPACE
index 12d01dc..af6559b 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "92943361811e20b96f4c979992a0b384711c6456",
+    commit = "523118896767024b74c17d087591eefe070055e9",
     #    local_path = "/home/<user>/projects/bazlets",
 )