Configuration in settings file

[etj]

We may add in this app settings these lines, so taht secrets are configured in the .env file:

DATACITE_API_URL=os.getenv("DATACITE_API_URL", "https://api.test.datacite.org")
DATACITE_API_USERNAME=os.getenv("DATACITE_API_USERNAME", "username_not_configured")
DATACITE_API_PASSWORD=os.getenv("DATACITE_API_PASSWORD", "password_not_configured")
DATACITE_EVENT=os.getenv("DATACITE_EVENT", 'draft')
DATACITE_PREFIX=os.getenv("DATACITE_PREFIX", "datacite_prefix_not_configured")
DATACITE_CREATOR=os.getenv("DATACITE_CREATOR", "")
DATACITE_CREATOR_TYPE=os.getenv("DATACITE_CREATOR_TYPE", "Organizational")
DATACITE_PUBLISHER=os.getenv("DATACITE_PUBLISHER", "")
DATACITE_DETAIL_URL=os.getenv("DATACITE_DETAIL_URL", "https://handle.test.datacite.org")