protofsm: use updated GoroutineManager API

Update to use the latest version of the GoroutineManager which takes a
context via the `Go` method instead of the constructor.

go.mod

@@ -36,7 +36,7 @@ require (
 	github.com/lightningnetwork/lightning-onion v1.2.1-0.20240712235311-98bd56499dfb
 	github.com/lightningnetwork/lnd/cert v1.2.2
 	github.com/lightningnetwork/lnd/clock v1.1.1
-	github.com/lightningnetwork/lnd/fn/v2 v2.0.2
+	github.com/lightningnetwork/lnd/fn/v2 v2.0.4
 	github.com/lightningnetwork/lnd/healthcheck v1.2.6
 	github.com/lightningnetwork/lnd/kvdb v1.4.12
 	github.com/lightningnetwork/lnd/queue v1.1.1