Add definition for Sigstore's DSSE signature extension #183

	#
	# Copyright 2022 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: Check Python build

	permissions:
	contents: read

	on:
	push:
	paths:
	- '**.proto'
	- 'gen/pb-python/**'
	pull_request:
	paths:
	- '**.proto'
	- 'gen/pb-python/**'

	jobs:
	build:
	strategy:
	matrix:
	python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
	fail-fast: false

	runs-on: ubuntu-latest

	steps:
	- uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
	- name: Set up Python ${{ matrix.python-version }}
	uses: actions/setup-python@65d7f2d534ac1bc67fcd62888c5f4f3d2cb2b236 # v4.7.1
	with:
	python-version: ${{ matrix.python-version }}

	- name: Build
	run: \|
	cd gen/pb-python
	python -m venv env && source env/bin/activate
	python -m pip install --upgrade pip
	python -m pip install .[dev]

	python -m build

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