Update `default.mixed` to `default.qubit.legacy` in `test_qnode_legacy.py` #55471

	name: Formatting check
	on:
	pull_request:
	types:
	- opened
	- reopened
	- synchronize
	- ready_for_review

	concurrency:
	group: ${{ github.workflow }}-${{ github.ref }}
	cancel-in-progress: true

	jobs:
	determine_runner:
	if: github.event.pull_request.draft == false
	name: Determine runner type to use
	uses: ./.github/workflows/determine-workflow-runner.yml
	with:
	default_runner: ubuntu-latest

	black-pylint:
	if: github.event.pull_request.draft == false
	needs: [determine_runner]
	runs-on: ${{ needs.determine_runner.outputs.runner_group }}

	steps:
	- name: Set up Python
	uses: actions/setup-python@v5
	with:
	python-version: "3.10"

	- name: Install dependencies
	run: pip install black pylint==2.7.4 isort==5.13.2

	- uses: actions/checkout@v4

	- name: Run Black
	run: \|
	black -t py310 -t py311 -t py312 -l 100 pennylane/ --check
	black -t py310 -t py311 -t py312 -l 100 tests/ --check

	- name: Run isort
	run: \|
	isort --py 312 --profile black -l 100 -o autoray -p ./pennylane --skip __init__.py --filter-files ./pennylane --check
	isort --py 312 --profile black -l 100 -o autoray -p ./pennylane --skip __init__.py --filter-files ./tests --check

	- name: Run Pylint (source files)
	if: always()
	run: pylint --rcfile .pylintrc $(find pennylane -name "*.py")

	- name: Run Pylint (test files)
	if: always()
	run: pylint --rcfile tests/.pylintrc $(find tests -name "*.py")

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