Fix .arcconfig not working with latest arcanist version

.arcconfig

 {
 	"project_id" : "Blender Dev Tools",
 	"conduit_uri" : "https://developer.blender.org/",
+	"phabricator.uri" : "https://developer.blender.org/",
 	"git.default-relative-commit" : "origin/master",
 	"arc.land.update.default" : "rebase"
-}
\ No newline at end of file
+}