fix(zeebe): waitForReady deadline not miliseconds, but date (#148)

"waitForReady" was called with a deadline of 10000 milliseconds.

But the method 'watchConnectivityState' used by 'waitForReady', wants a deadline date.

So this fix is to set the deadline date at now + 10s

src/zeebe/lib/GrpcClient.ts

@@ -276,7 +276,7 @@ export class GrpcClient extends EventEmitter {
 		})
 		this.listNameMethods = []
 
-		this.client.waitForReady(10000, (error) =>
+		this.client.waitForReady(new Date(Date.now() + 10000), (error) =>
 			error
 				? this.emit(MiddlewareSignals.Event.Error, error)
 				: this.emit(MiddlewareSignals.Event.Ready)