Update go mod and vendor in client dir to 0.28.0

client/vendor/k8s.io/apimachinery/pkg/labels/labels.go

@@ -77,6 +77,8 @@ func (ls Set) AsValidatedSelector() (Selector, error) {
 // perform any validation.
 // According to our measurements this is significantly faster
 // in codepaths that matter at high scale.
+// Note: this method copies the Set; if the Set is immutable, consider wrapping it with ValidatedSetSelector
+// instead, which does not copy.
 func (ls Set) AsSelectorPreValidated() Selector {
 	return SelectorFromValidatedSet(ls)
 }