It feels like this is missing the ability to specific an exact media query for sizes

```
 <Picture
  src={[
    require(`/assets/images/leaders/${imgSrc}?sizes=435`),
    require(`/assets/images/leaders/${imgSrc}?sizes=946`),
  ]}
  breakpoints={['(orientation: landscape)']}
/>
```

`breakpoints` only takes in a `px` value, but seems to be missing the ability to pass in the actual media query itself.

Should we put in a PR or is there a workaround?