Fix wrong swarming url

Extra .appspot.com

Change-Id: I4065a75fbe58453e5b90ccfa3b2ababd2e34fcee
diff --git a/main.star b/main.star
index d79510b..4958be1 100755
--- a/main.star
+++ b/main.star
@@ -17,7 +17,7 @@
     milo = "luci-milo.appspot.com",
     notify = "luci-notify.appspot.com",
     scheduler = "luci-scheduler.appspot.com",
-    swarming = "chromium-swarm.appspot.com.appspot.com",
+    swarming = "chromium-swarm.appspot.com",
     tricium = "tricium-prod.appspot.com",
 
     bindings = [