Update Buck to latest version

Change-Id: Ic99dd9da2acb0dc807f98860c5336913056fddc0
diff --git a/BUCK b/BUCK
index d658b92..736bd7c 100644
--- a/BUCK
+++ b/BUCK
@@ -31,7 +31,6 @@
   name = 'replication_tests',
   srcs = glob(['src/test/java/**/*.java']),
   labels = ['replication'],
-  source_under_test = [':replication__plugin'],
   deps = [
     ':replication__plugin',
     '//gerrit-acceptance-framework:lib',