Add new JSON output: supported Python versions #7

	---
	name: PyPA sample project tested over declared interpreters

	on:
	push:
	branches: [main]
	pull_request:
	workflow_dispatch:

	env:
	FORCE_COLOR: "1" # Make tools pretty.

	jobs:
	build-package:
	name: Build & verify package
	runs-on: ubuntu-latest

	steps:
	- uses: actions/checkout@v4
	with:
	repository: pypa/sampleproject
	path: sampleproject
	- uses: actions/checkout@v4
	with:
	path: action
	- uses: ./action
	id: baipp
	with:
	path: sampleproject

	outputs:
	python-versions: ${{ steps.baipp.outputs.supported_pythons_job_matrix_value }}

	test-package:
	needs: build-package
	runs-on: ubuntu-latest
	strategy:
	matrix: ${{ fromJson(needs.build-package.outputs.python-versions) }}

	steps:
	- uses: actions/setup-python@v4
	with:
	python-version: ${{ matrix.python-version }}
	- run: pip install pytest
	- uses: actions/download-artifact@v4
	with:
	name: Packages
	path: dist
	- run: pip install dist/*.whl
	- uses: actions/checkout@v4
	with:
	repository: pypa/sampleproject
	- run: python -Im pytest tests/

	...

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