go.mod: require correct version of k8s.io/client-go directly

Author: joelanford

go.mod

@@ -6,8 +6,6 @@ require (
 	github.com/stretchr/testify v1.5.1
 	k8s.io/api v0.18.2
 	k8s.io/apimachinery v0.18.2
-	k8s.io/client-go v12.0.0+incompatible
+	k8s.io/client-go v0.18.2
 	sigs.k8s.io/controller-runtime v0.6.0
 )
-
-replace k8s.io/client-go => k8s.io/client-go v0.18.2