Add Sponsor button on GitHub repo

https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/displaying-a-sponsor-button-in-your-repository

added SprintTo review label

assigned to @pnicolas

mentioned in commit f4dcf8bc

added SprintDone label and removed SprintTo review label

https://github.com/savoirfairelinux/jami-client-android

lfx_crowdfunding icon is not loading as expected, I hope it will be fix by GitHub soon

mentioned in commit jami-daemon@8c1c74f0

mentioned in commit jami-client-ios@1cc30892

mentioned in commit jami-client-qt@7736b5c3

closed