TUN-3375: Upgrade coredns and prometheus dependencies

vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/header.go

@@ -52,6 +52,15 @@ func (hs *Headers) Del(name string) {
 	}
 }
 
+// Clone returns a deep copy of the headers
+func (hs Headers) Clone() Headers {
+	o := make(Headers, 0, len(hs))
+	for _, h := range hs {
+		o.Set(h.Name, h.Value)
+	}
+	return o
+}
+
 func decodeHeaders(r io.Reader) (Headers, error) {
 	hs := Headers{}