Add `image_diff` comparison method for test output verification using images #3383

	name: Check test class names
	on:
	pull_request:
	paths:
	- '.ci/check_test_class_names.sh'
	- 'lib/galaxy_test/**'
	- 'test/**'
	jobs:
	test:
	name: Test
	runs-on: ubuntu-latest
	strategy:
	matrix:
	python-version: ['3.8']
	steps:
	- uses: actions/checkout@v3
	- uses: actions/setup-python@v4
	with:
	python-version: ${{ matrix.python-version }}
	- name: Cache pip dir
	uses: actions/cache@v3
	with:
	path: ~/.cache/pip
	key: pip-cache-${{ matrix.python-version }}-${{ hashFiles('requirements.txt') }}
	- name: Install Python dependencies
	run: pip install -r requirements.txt -r lib/galaxy/dependencies/dev-requirements.txt
	- name: Run tests
	run: .ci/check_test_class_names.sh

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