jiri: Switch fnl-start remote from github to googlesource.

Change-Id: Ia57080f4e825068e1400febc46d3fe1a54a41235
diff --git a/upgrade.go b/upgrade.go
index 382e18e..da6947f 100644
--- a/upgrade.go
+++ b/upgrade.go
@@ -88,7 +88,7 @@
 		argRemote = "https://vanadium.googlesource.com/manifest"
 		argName, argManifest = "manifest", "public"
 	case "fuchsia":
-		argRemote = "https://github.com/effenel/fnl-start.git"
+		argRemote = "https://fuchsia.googlesource.com/fnl-start"
 		argName, argManifest = "fnl-start", "manifest/fuchsia"
 	default:
 		return jirix.UsageErrorf("unknown upgrade kind %q", kind)