minor regression: `customdata` is sometimes a tuple 

This returns a numpy array in 4.14.3 and a tuple in 5.1.0:

```python
import plotly.express as px
fig = px.scatter(px.data.tips(), x="total_bill", y="tip", custom_data=["sex"])
fig.data[0].customdata
```

Ideally we would get back to the old behaviour if possible.