Does not allow for log level configuration

It does not seem to be possible to configure the log level of pino when using esc format. I would like to configure the log level per environment and this does not seem possible with esc format.

## Current Behaviour

```js
const logger = pino(ecsFormat({ serviceName: "helloworld" }))
```

## Expected Behaviour

```js
const logger = pino(ecsFormat({ serviceName: "helloworld", logLevel: "info" }))
```