Implement `drop_unmatched`, `keep_unmatched` and `add_dim` #2

	name: Workflow for Codecov
	on: [pull_request]
	jobs:
	run:
	runs-on: ubuntu-latest
	steps:
	- name: Checkout
	uses: actions/checkout@v4
	with:
	fetch-depth: 0
	- name: Set up Python 3.7
	uses: actions/setup-python@v4
	with:
	python-version: '3.7'
	- name: Install dependencies
	run: pip install .[dev]
	- name: Run tests and collect coverage
	run: pytest --cov=src/pyoframe
	- name: Upload coverage to Codecov
	uses: codecov/codecov-action@v4-beta
	with:
	flags: smart-tests
	verbose: true
	env:
	CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}

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