Supports searching in array

when given:

```json
{
    "_id": "63d08b89ff6175f6a2807d0b",
    "index": 9999,
   "tags": [
      "warrior",
      "magical"
    ]
}
```

To be expected:

```py
condition = Key('tags').isin('magical')
result = db.find(condition)
```
