add github sponsors

also: reorder

.github/FUNDING.yml

@@ -1,6 +1,6 @@
 # These are supported funding model platforms
 
-# github: # Replace with up to 4 GitHub Sponsors-enabled usernames e.g., [user1, user2]
+github: borgbackup
 liberapay: borgbackup
-custom: ['https://www.borgbackup.org/support/fund.html']
 open_collective: borgbackup
+custom: ['https://www.borgbackup.org/support/fund.html']