Update getCategory so it can take a query too

In `src/express/category-handler.js`, update:

```
const response = await SHIFTClient.getCategoryV1(req.params.id)
```
To
```
const response = await SHIFTClient.getCategoryV1(req.params.id, req.query)
```

This is so custom queries can be passed through, such as adding `include: 'template'`

Will also need to update shift-node-api to accept queries