build: update to btcwallet version with async mempool scan

This version of btcwallet demotes some spammy logs (txns replaced in the
mempool), and makes the initial mempool scan async.

Fixes https://github.com/lightningnetwork/lnd/issues/7640

go.sum

@@ -89,8 +89,8 @@ github.com/btcsuite/btcd/chaincfg/chainhash v1.0.2/go.mod h1:7SFka0XMvUgj3hfZtyd
 github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f h1:bAs4lUbRJpnnkd9VhRV3jjAVU7DJVjMaK+IsvSeZvFo=
 github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f/go.mod h1:TdznJufoqS23FtqVCzL0ZqgP5MqXbb4fg/WgDys70nA=
 github.com/btcsuite/btcutil v0.0.0-20190425235716-9e5f4b9a998d/go.mod h1:+5NJ2+qvTyV9exUAL/rxXi3DcLg2Ts+ymUAY5y4NvMg=
-github.com/btcsuite/btcwallet v0.16.8 h1:ADMormFSOBMANB/ZWvU00VDnFelZXY9Uyc9wW0dNFzM=
-github.com/btcsuite/btcwallet v0.16.8/go.mod h1:ynC16HgMU03dYyUit6b0+IZjDg9KVnr2VNLie9ZXG1I=
+github.com/btcsuite/btcwallet v0.16.9 h1:hLAzEJvsiSn+r6j374G7ThnrYD/toa+Lv7l1Rm6+0oM=
+github.com/btcsuite/btcwallet v0.16.9/go.mod h1:T3DjEAMZYIqQ28l+ixlB6DX4mFJXCX8Pzz+yACQcLsc=
 github.com/btcsuite/btcwallet/wallet/txauthor v1.3.2 h1:etuLgGEojecsDOYTII8rYiGHjGyV5xTqsXi+ZQ715UU=
 github.com/btcsuite/btcwallet/wallet/txauthor v1.3.2/go.mod h1:Zpk/LOb2sKqwP2lmHjaZT9AdaKsHPSbNLm2Uql5IQ/0=
 github.com/btcsuite/btcwallet/wallet/txrules v1.2.0 h1:BtEN5Empw62/RVnZ0VcJaVtVlBijnLlJY+dwjAye2Bg=