cobraz/pubsub-http-handler

# Migrate from v2 and v3

With Fastify v4, we've changed some of the API for the PubSubHandler and bumped
node to v16. Most of the changes aren't an issue for most users.

- Bumped node to v16
- Bumped fastify to v4
- The `address` attribute is changed to `host` to align with Fastify
- With `ajv` version 7 and above, `ajvTypeBoxPlugin` is required. (only required
  when using the Fastify plugin)
- Added `pino` logger to Cloud Functions
- Added `log` to handler (see example down below)

# Using `pubSubFastifyPlugin` in v4

```typescript
import Fastify from 'fastify';
import { TypeBoxTypeProvider } from '@fastify/type-provider-typebox';
import { pubSubFastifyPlugin } from 'pubsub-http-handler';

interface MyHandler {
  hello: string;
  world: string;
}

const server = async () => {
  const handler: PubSubHandler<MyHandler> = ({ message, data }) => {
    // `message` contains attributes, data (as string), messageId
    // `data` contains a base64 decoded JSON serialized object (type is MyHandler in the example)

    ...
  };

  const fastify = Fastify().withTypeProvider<TypeBoxTypeProvider>()

  fastify.register(pubSubFastifyPlugin)
  fastify.listen();
};
```

# Improved logging

The `handler` now comes with a `log` attribute which contains a `pino` instance.

```typescript
import { TypeBoxTypeProvider } from '@fastify/type-provider-typebox';
import Fastify from 'fastify';
import { PubSubHandler, pubSubFastifyPlugin } from '../src';

interface HandlerArguments {
  name: string;
  party: {
    name: string;
  };
  bookingId: string;
}

const server = () => {
  const fastify = Fastify().withTypeProvider<TypeBoxTypeProvider>();

  const handler: PubSubHandler<HandlerArguments> = ({ data, log }) => {
    const { name, party, bookingId } = data;
    log.info(`${name} from ${party.name} had a booking with id ${bookingId}`);
  };

  fastify.register(pubSubFastifyPlugin, { handler });

  fastify.server.listen(8000);
};

server();
```