Add activist to data.json

[Vince155]

activist is a network for political action empowering individual to collaborate on issues that matter to them.

[andrewtavis]

Thanks for adding us here, @Vince155 :) If a maintainer here has any questions, myself or the community would be happy to address them 😊

[andrewtavis]

Thanks so much for the care to edit the entry, @sammyhori!

[sammyhori]

That's okay, thank you for the entry :)