Update go dependencies

vendor/k8s.io/client-go/tools/cache/index.go

@@ -23,12 +23,15 @@ import (
 	"k8s.io/apimachinery/pkg/util/sets"
 )
 
-// Indexer is a storage interface that lets you list objects using multiple indexing functions.
-// There are three kinds of strings here.
-// One is a storage key, as defined in the Store interface.
-// Another kind is a name of an index.
-// The third kind of string is an "indexed value", which is produced by an
-// IndexFunc and can be a field value or any other string computed from the object.
+// Indexer extends Store with multiple indices and restricts each
+// accumulator to simply hold the current object (and be empty after
+// Delete).
+//
+// There are three kinds of strings here:
+// 1. a storage key, as defined in the Store interface,
+// 2. a name of an index, and
+// 3. an "indexed value", which is produced by an IndexFunc and
+//    can be a field value or any other string computed from the object.
 type Indexer interface {
 	Store
 	// Index returns the stored objects whose set of indexed values