Uncomment upgrade for 5.1.0 (#9040)

model/version.go

@@ -13,6 +13,7 @@ import (
 // It should be maintained in chronological order with most current
 // release at the front of the list.
 var versions = []string{
+	"5.1.0",
 	"5.0.0",
 	"4.10.0",
 	"4.9.0",