Allow Sponsorship via GitHub

[MischaBarm]

Dear Tailwind Team,

I noticed that sponsoring is currently only available through the Tailwind CSS website. To reach a broader audience, it might be worth considering enabling sponsorship directly through GitHub as well.

This would allow supporters to choose donation amounts that better fit their preferences. Additionally, some community members may simply want to contribute without receiving any benefits, unlike the current Tailwind Insiders program. GitHub Sponsors could offer a straightforward way to support the project in that spirit.

Thanks for the great work!