Root route doesn't actually return JSON formatted object

The root route returns the `Debug` formatted rust struct for a `Dataset` not a JSON formatted object of `Dataset.list`

Actual output:
```
Dataset { list: [Record { name: "Mission 1", split: Test }, Record { name: "Mission 2", split: Train }, Record { name: "Mission 3", split: Validation }, Record { name: "Mission 4", split: Train }, Record { name: "Weirds-nasdlf!!@$#123__321", split: Train }, Record { name: "testing new thing", split: Unknown }] }
```

Desired output (new lines included for clarity, not expected in output):
```
{
[
{ name: "Mission 1", split: Test },
{ name: "Mission 2", split: Train },
{ name: "Mission 3", split: Validation },
{ name: "Mission 4", split: Train },
{ name: "Weirds-nasdlf!!@$#123__321", split: Train },
{ name: "testing new thing", split: Unknown }
]
}
```