changes required when switching from `master` to `main`

[gvwilson]

• https://github.com/plotly/plotly.py/blob/f239366bbc62c97031f9312dbf3a7741ff91fd77/commands.py#L245?target=https://github.com

[alexcjohnson]

Let's just flip this switch already... if it breaks anything it won't be for our users, only for Plotly devs and contributors and we can sort it out ourselves after making the change.