Client go upgrade v6 (#352)

There are shortcuts in this code, i.e. we created the deepcopy function
by using the deepcopy package instead of the generated code, that will
be addressed once migrated to client-go v8. Also, some objects,
particularly statefulsets, are still taken from v1beta, this will also
be addressed in further commits once the changes are stabilized.

pkg/controller/postgresql.go

@@ -147,12 +147,12 @@ func (d *crdDecoder) Decode() (action watch.EventType, object runtime.Object, er
 
 func (c *Controller) clusterWatchFunc(options metav1.ListOptions) (watch.Interface, error) {
 	options.Watch = true
+	// MIGRATION: FieldsSelectorParam(nil)
 	r, err := c.KubeClient.CRDREST.
 		Get().
 		Namespace(c.opConfig.WatchedNamespace).
 		Resource(constants.PostgresCRDResource).
 		VersionedParams(&options, metav1.ParameterCodec).
-		FieldsSelectorParam(nil).
 		Stream()
 
 	if err != nil {