Added new constants for fields, types, and directories. All directory constants are relative to the `MEDS_ROOT` dir. #67

	name: Run tests

	on:
	push:
	branches: [ "main" ]
	pull_request:
	branches: [ "main" ]

	jobs:
	build:

	runs-on: ubuntu-latest

	strategy:
	matrix:
	python-version: ["3.10"]

	steps:
	- uses: actions/checkout@v3
	- name: Set up Python ${{ matrix.python-version }}
	uses: actions/setup-python@v3
	with:
	python-version: ${{ matrix.python-version }}
	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	python -m pip install flake8 pytest
	- name: Install MEDS
	run: python -m pip install .
	- name: Run tests
	run: \|
	pytest -v

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