build: update btcwallet and zmq dependencies

* We address an issue where we would unnecessarily time out bitcoind ZMQ
  connections if there are no messages to be read. This would cause
  connections to be torn down, which would then trigger the reconnection
  logic and prevent us from detecting this issue.

* A new sanity check within the wallet is done to prevent adding
  unconfirmed transactions that the wallet has already recognized as
  confirmed.

go.mod

@@ -8,7 +8,7 @@ require (
 	github.com/btcsuite/btcd v0.0.0-20190629003639-c26ffa870fd8
 	github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f
 	github.com/btcsuite/btcutil v0.0.0-20190425235716-9e5f4b9a998d
-	github.com/btcsuite/btcwallet v0.0.0-20190628225330-4a9774585e57
+	github.com/btcsuite/btcwallet v0.0.0-20190712034938-7a3a3e82cbb6
 	github.com/btcsuite/fastsha256 v0.0.0-20160815193821-637e65642941
 	github.com/coreos/bbolt v1.3.2
 	github.com/davecgh/go-spew v1.1.1