Add mediatype string builder to bundle package #530

	# Copyright 2023 The Sigstore Authors.
	#
	# 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
	#
	# http://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.

	name: Verify

	on: [push, pull_request]

	permissions:
	contents: read

	jobs:
	license-check:
	name: license boilerplate check
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@9bb56186c3b09b4f86b1c65136769dd318469633 # v4.1.2
	- uses: actions/setup-go@0c52d547c9bc32b1aa3301fd7a9cb496313a4491 # v5.0.0
	with:
	go-version-file: './go.mod'
	check-latest: true
	- name: Install addlicense
	run: go install github.com/google/addlicense@v1.1.1
	- name: Check license headers
	run: \|
	set -e
	addlicense -check -l apache -c 'The Sigstore Authors' -ignore "third_party/*" -v

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