Add settings test

[machikoyasuda]

closes #54

What this PR does:

• Adds 1 test to the test_settings file - this test should test that a new .env file with a different INPUT_HASH_ALGO variable will appropriately set that new value to settings.INPUT_HASH_ALGO.
• Adds 1 new .env.settingstest file to be used on the new test, with the custom marker, @pytest.mark.settingstest
• Adds 1 new pytest.ini file to register the new custom marker
• Changes the run_test GitHub Action to run the test suite twice: on the first run, test all but the @pytest.mark.settingstest spec, and on the second run, run only that spec. In between the two runs, run source tests/.env.settingstest so that the test environment can read from the 2nd .env file
• Refactors test_database and test_hash with parameterization

How I'm using the custom @pytest.mark

1. Register the mark in pytest.ini - to document the mark and what it means. This isn't required for implementation, but is highly recommended:

[pytest]
markers =
    settingstest: mark a test to be run with .env.settingstest

2. Use the custom mark in a method: @pytest.mark.settingstest:

@pytest.mark.settingstest
def test_hash_settings_env():
    assert settings.INPUT_HASH_ALGO == "sha512"

3. Call pytest using the mark:

## Run all test with the mark
coverage run -m pytest -m settingstest

## Run all tests without the mark
coverage run -m pytest -m "not settingstest"

This is what the output looks like:

## Run all test with the mark
======================= 1 passed, 23 deselected in 0.10s =======================

## Run all tests without the mark
======================= 23 passed, 1 deselected in 2.09s =======================

[thekaveman]

I'm liking the parameterized tests!

[angela-tran]

The parameterization and the custom marks look good to me!

I agree with @thekaveman 's feedback that we could remove those redundant lines in the workflow.

[thekaveman]

🚀

[angela-tran]

👍