fix: Remove await from listener.forward() on NgrokProxy class

[zenizh]

To prevent subsequent processing from stopping, I removed await from the call to listener.forward() in the NgrokProxy class.

Reason

listener.forward() returns a Promise, but this Promise does not seem to resolve until the forwarding task is complete. Therefore, using await causes subsequent processing to stop, and the CLI no longer works properly.

In fact, when the following command was executed in the current main branch, nothing was output to the terminal:

$ liff-cli serve \
  --liff-id 1234567890-AbcdEfgh \
  --url http://localhost:5173 \
  --proxy-type ngrok

(no output)

Internally, the endpoint was created on Ngrok, but the endpoint URL on the LINE Developers Console was not updated.

In the official documentation sample, listener.forward() is also called without await:

async function create_listener() {
  const session = await new ngrok.NgrokSessionBuilder().authtokenFromEnv().connect();
  const listener = await session.httpEndpoint().listen();
  console.log("Ingress established at:", listener.url());
  listener.forward("localhost:8081");
}

https://github.com/ngrok/ngrok-javascript?tab=readme-ov-file#builders

After removing await, ngrok processed normally, and the endpoint URL on the LINE Developers Console was also updated.

[CLAassistant]

All committers have signed the CLA.

[odanado]

LGTM
Thank you!