TST: Create test workflow

[KCollins]

• Create test workflow.
• Implement get_r2r_url tests (below)
• Implement coveralls, badge

Gemini wrote these nice tests for get_r2r_url, which will make a good starting point:

if __name__ == "__main__":
    # Test cases
    try:
        print(f"Default behavior (no args):")
        get_r2r_url()
    except ValueError as e:
        print(f"Error (expected): {e}")

    print(f"\nURL for cruise_id 'RR2402': {get_r2r_url(cruise_id='RR2402')}")
    print(f"URL for vessel 'Revelle': {get_r2r_url(vessel_name='Revelle')}")
    print(f"URL for DOI '10.7284/910464': {get_r2r_url(doi='10.7284/910464')}")
    print(f"URL for another DOI '10.1234/56789': {get_r2r_url(doi='10.7284/910464')}")


    try:
        get_r2r_url(cruise_id='RR2402', doi='10.xxxx/yyyyy')
    except ValueError as e:
        print(f"\nError (expected): {e}")

    try:
        get_r2r_url(doi='10.xxxx/yyyyy', vessel_name='Atlantis')
    except ValueError as e:
        print(f"Error (expected): {e}")