Fix process-based non-determinism in `SparsePauliOp.to_matrix` #373

	name: QPY

	on:
	push:
	branches:
	- 'main'
	- 'stable/*'
	pull_request:
	merge_group:
	concurrency:
	group: ${{ github.repository }}-${{ github.ref }}-${{ github.head_ref }}-${{ github.workflow }}
	cancel-in-progress: ${{ github.event_name == 'pull_request' }}

	jobs:
	backward_compat:
	if: github.repository_owner == 'Qiskit'
	name: Backwards compatibility
	runs-on: ubuntu-latest

	steps:
	- uses: actions/checkout@v4

	- uses: actions/setup-python@v5
	with:
	python-version: '3.9'

	- uses: dtolnay/rust-toolchain@stable

	- uses: actions/cache@v4
	with:
	path: test/qpy_compat/qpy_cache
	# The hashing is this key can be too eager to invalidate the cache,
	# but since we risk the QPY tests failing to update if they're not in
	# sync, it's better safe than sorry.
	key: qpy-${{ hashFiles('test/qpy_compat/**') }}

	- name: Run QPY backwards compatibility tests
	working-directory: test/qpy_compat
	run: ./run_tests.sh

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