Support better support collection of tokens

[dwightwatson]

• Update dependencies
• Remove spatie/enum dependency
• Support single/array/collection of tokens
• Handle value changes to Visibility enum

[msonowal]

ping @atymic

[dwightwatson]

I can merge this myself. However I am unable to test this as I don't currently have access to an Android project.

As noted in the other issue I'd love some people to test this and see if it works well. It drops some older PHP versions and introduces other changes.

[grEvenX]

@dwightwatson Anything in particular you would want to test? I tested basic sending on Android with setting a title and body and it was sent fine 👍

[dwightwatson]

Nope - that's a great sanity check - thanks for that.

Maybe I'll merge this and tag as v3, that way it can live alongside v2 and both will support Laravel 10. Can iron out any issues as they arise but users can always fall back to v2 if they need.