Usability: y_axis option for PublishLabelOptions would be better as an enumeration

[tlisonbee]

Current API takes a 0 or 1 for left vs. right

            PublishLabelOptions(
                y_axis=0
            ),
            PublishLabelOptions(
                y_axis=1
            )

Suggested API is something like:

            PublishLabelOptions(
                y_axis=YAxis.left
            ),
            PublishLabelOptions(
                y_axis=YAxis.right
            )