button label loading state

[Hallidayo]

What kind of change does this PR introduce?

Bug Fix

What is the current behavior?

On the views the button label does not change when the button is not in a loading state.

What is the new behavior?

Button label now changes:

https://github.com/supabase/auth-ui/assets/22655069/89fa22ec-2acc-48f9-895f-11e10a5bb44a

Additional context

Closes #219

[scosman]

@Hallidayo thanks!