Upgrade tukaani-xz to 1.6

Change-Id: I8d6e9329fc16902ebdfa1a55fbf79c558fa2c323
diff --git a/WORKSPACE b/WORKSPACE
index 8e4bae3..fe0ca1d 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -426,8 +426,8 @@
 
 maven_jar(
     name = "tukaani_xz",
-    artifact = "org.tukaani:xz:1.4",
-    sha1 = "18a9a2ce6abf32ea1b5fd31dae5210ad93f4e5e3",
+    artifact = "org.tukaani:xz:1.6",
+    sha1 = "05b6f921f1810bdf90e25471968f741f87168b64",
 )
 
 # When upgrading Lucene, make sure it's compatible with Elasticsearch