Point to glitch-soc source and not tootsuite on the public page

(hello AGPLv3)

lib/mastodon/version.rb

@@ -33,7 +33,7 @@ module Mastodon
     end
 
     def source_base_url
-      'https://github.com/tootsuite/mastodon'
+      'https://github.com/glitch-soc/mastodon'
     end
 
     # specify git tag or commit hash here