Update to k8s v1.20

vendor/golang.org/x/xerrors/errors.go

@@ -0,0 +1,33 @@
+// Copyright 2011 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 file.
+
+package xerrors
+
+import "fmt"
+
+// errorString is a trivial implementation of error.
+type errorString struct {
+	s     string
+	frame Frame
+}
+
+// New returns an error that formats as the given text.
+//
+// The returned error contains a Frame set to the caller's location and
+// implements Formatter to show this information when printed with details.
+func New(text string) error {
+	return &errorString{text, Caller(1)}
+}
+
+func (e *errorString) Error() string {
+	return e.s
+}
+
+func (e *errorString) Format(s fmt.State, v rune) { FormatError(e, s, v) }
+
+func (e *errorString) FormatError(p Printer) (next error) {
+	p.Print(e.s)
+	e.frame.Format(p)
+	return nil
+}