Uncomment upgrade for 3.9 (#6336)

* Uncomment upgrade for 3.9

* Add 3.9.0 to model/version.go

model/version.go

@@ -13,6 +13,7 @@ import (
 // It should be maitained in chronological order with most current
 // release at the front of the list.
 var versions = []string{
+	"3.9.0",
 	"3.8.0",
 	"3.7.0",
 	"3.6.0",