Downgrade Kubernetes vendor version

Multus community decide that multus support the Kubernetes that
Kubernetes community supports, so changed vendor code to the
oldest version of currently supported.

vendor/github.com/google/go-cmp/cmp/report.go

@@ -1,54 +0,0 @@
-// Copyright 2017, The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
-
-package cmp
-
-// defaultReporter implements the reporter interface.
-//
-// As Equal serially calls the PushStep, Report, and PopStep methods, the
-// defaultReporter constructs a tree-based representation of the compared value
-// and the result of each comparison (see valueNode).
-//
-// When the String method is called, the FormatDiff method transforms the
-// valueNode tree into a textNode tree, which is a tree-based representation
-// of the textual output (see textNode).
-//
-// Lastly, the textNode.String method produces the final report as a string.
-type defaultReporter struct {
-	root *valueNode
-	curr *valueNode
-}
-
-func (r *defaultReporter) PushStep(ps PathStep) {
-	r.curr = r.curr.PushStep(ps)
-	if r.root == nil {
-		r.root = r.curr
-	}
-}
-func (r *defaultReporter) Report(rs Result) {
-	r.curr.Report(rs)
-}
-func (r *defaultReporter) PopStep() {
-	r.curr = r.curr.PopStep()
-}
-
-// String provides a full report of the differences detected as a structured
-// literal in pseudo-Go syntax. String may only be called after the entire tree
-// has been traversed.
-func (r *defaultReporter) String() string {
-	assert(r.root != nil && r.curr == nil)
-	if r.root.NumDiff == 0 {
-		return ""
-	}
-	ptrs := new(pointerReferences)
-	text := formatOptions{}.FormatDiff(r.root, ptrs)
-	resolveReferences(text)
-	return text.String()
-}
-
-func assert(ok bool) {
-	if !ok {
-		panic("assertion failure")
-	}
-}