Cell hash arbitrary values are no longer applied directly to the cell. Instead, use the `style:` attribute.

Example:

```ruby
# before
def table_data
  [{
    cells: [{
      title: "My cell title",
      backgroundColor: UIColor.redColor
    }]
  }]
end

# after
def table_data
  [{
    cells: [{
      title: "My cell title",
      style: {
        backgroundColor: UIColor.redColor
      }
    }]
  }]
end
```