Update replication plugin to the latest revision

The latest revision includes:

- Serialize pushes to each destination URI

Change-Id: Iee3c77f671cb82f689868f0b0f2db0cde8c6dabf
diff --git a/plugins/replication b/plugins/replication
index 7ec017f..3fffd16 160000
--- a/plugins/replication
+++ b/plugins/replication
@@ -1 +1 @@
-Subproject commit 7ec017fbac3f34fffc7af175d0dec181d18c33f2
+Subproject commit 3fffd16403c1d3a4d6f0b13e9f33f4f78df1f6b4