Upgrade bazlets to latest stable-2.15

Includes further fixes for --incompatible_disallow_legacy_java_provider.

Change-Id: Ibece8324414affb6442a39caf9dcec1d7a37f4c0

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 2c2e15d..79e7727 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "1aa9482d30e8873e6d3e1e75dc307a43aae0482e",
+    commit = "5f03aec7c72e743079ea2ecad5530f4684ca7d45",
     #local_path = "/home/<user>/projects/bazlets",
 )