Reconnect with infinite retry attempts/timeout does not respond to `close()`

I'm implementing a worker process with the following requirements:

- The notification listener should retry reconnecting indefinitely. (Infinite retry attempts, no timeout)
- The worker process should respond to `SIGINT` signals, and gracefully terminate.

The "reconnect" loop does not respond to any signal from calling `close()`, so it will attempt to reconnect indefinitely. The promise hangs around and prevents the process from closing normally. (I've even seen odd behaviour where I've killed the process using `kill -15 1234`, and it returns to the terminal prompt, but I still see "reconnecting" messages logged. 😳)

A rough sketch:

```typescript
import createPostgresSubscriber from "pg-listen";

async function demo() {
try {
process.on("SIGTERM", () => {
console.log("Attempting graceful termination");
await subscriber.close();
console.log("Subscriber closed");
});

var subscriber = createPostgresSubscriber(
{
connectionString:
"postgresql://invalid_user:invalid_password@localhost/postgres"
},
{
retryInterval: 500,
retryTimeout: Number.POSITIVE_INFINITY
}
);

this.subscriber.events.on("reconnect", () => {
console.log(`Reconnecting...`);
});

await subscriber.connect();
await subscriber.listenTo("some_channel");
} catch (err) {
console.error(err);
}
}

demo().then(
() => console.log("Done"),
err => console.error("Error", err)
);
```