add side effect imports for azure and gcp auth (#944)

* add side effect imports for azure and gcp auth

Author: jasonhawkharris

cmd/src/validate_kube.go

@@ -7,6 +7,8 @@ import (
 	"path/filepath"
 
 	"k8s.io/client-go/kubernetes"
+	_ "k8s.io/client-go/plugin/pkg/client/auth/azure"
+	_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
 	"k8s.io/client-go/tools/clientcmd"
 	"k8s.io/client-go/util/homedir"