multi: update to latest version of btcd in submodules

The main package has already been updated, but here we update the
submodules as well that only import things to use a constant or so here
and there.

tools/go.mod

@@ -3,10 +3,8 @@ module github.com/lightningnetwork/lnd/tools
 go 1.16
 
 require (
-	github.com/btcsuite/btcd v0.23.1
-	github.com/elazarl/go-bindata-assetfs v1.0.1 // indirect
+	github.com/btcsuite/btcd v0.23.3
 	github.com/golangci/golangci-lint v1.46.2
 	github.com/ory/go-acc v0.2.6
 	github.com/rinchsan/gosimports v0.1.5
-	github.com/stephens2424/writerset v1.0.2 // indirect
 )