Clean vendor dependencies

vendor/github.com/opencontainers/go-digest/digester.go

@@ -1,39 +0,0 @@
-// Copyright 2017 Docker, Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package digest
-
-import "hash"
-
-// Digester calculates the digest of written data. Writes should go directly
-// to the return value of Hash, while calling Digest will return the current
-// value of the digest.
-type Digester interface {
-	Hash() hash.Hash // provides direct access to underlying hash instance.
-	Digest() Digest
-}
-
-// digester provides a simple digester definition that embeds a hasher.
-type digester struct {
-	alg  Algorithm
-	hash hash.Hash
-}
-
-func (d *digester) Hash() hash.Hash {
-	return d.hash
-}
-
-func (d *digester) Digest() Digest {
-	return NewDigest(d.alg, d.hash)
-}