Subscription not updating
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### Summary

<!-- Please detail the issue you'd like to discuss. -->

I am running the server as below

```js
import express from "express";
import { postgraphile, makePluginHook } from "postgraphile";
import fs from "fs";
import PgPubsub from "@graphile/pg-pubsub";

const pluginHook = makePluginHook([PgPubsub]);

const middleware = postgraphile(
  {
    database: process.env.DB_NAME,
    port: process.env.DB_PORT,
    host: process.env.DB_HOST,
    password: process.env.DB_PASSWORD,
    user: process.env.DB_USERNAME,
    sslmode: "require",
    ssl: {
      ca: fs.readFileSync("ca-certificate.crt"),
    },
  },
  "public",
  {
    watchPg: false,
    graphiql: true,
    enhanceGraphiql: true,
    retryOnInitFail: true,
    subscriptions: true,
    pluginHook,
    simpleSubscriptions: true,
  }
);
```

When I run the subscription I get immediate results but adding or removing records in the same table does not update the subscription results. Am I missing something here?

<img width="1632" alt="Screenshot 2022-06-27 at 5 46 26 PM" src="https://user-images.githubusercontent.com/80455750/175939131-d1349260-d458-44a7-860c-c1f91afefb46.png">


### Additional context

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      operating system, Node, PostgreSQL, Redis, etc. as relevant), software
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