enhance tests to also check use of empty string in `modextrapaths` #5133

	name: Static Analysis
	on: [push, pull_request]

	permissions:
	contents: read # to fetch code (actions/checkout)

	concurrency:
	group: ${{format('{0}:{1}:{2}', github.repository, github.ref, github.workflow)}}
	cancel-in-progress: true

	jobs:
	python-linting:
	strategy:
	matrix:
	python: [3.8, 3.9, '3.10', '3.11', '3.12', '3.13']
	include:
	- python: 3.7
	os: ubuntu-22.04
	fail-fast: false
	runs-on: ${{matrix.os \|\| 'ubuntu-24.04'}}
	steps:
	- uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # 4.2.2

	- name: set up Python
	uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5.4.0
	with:
	python-version: ${{ matrix.python-version }}

	- name: install Python packages
	run: \|
	pip install --upgrade pip
	pip install --upgrade flake8

	- name: Run flake8 to verify PEP8-compliance of Python code
	run: \|
	flake8

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