* Adds dev dependencies to requirements.txt and re-runs black on codebase
* Adds test and code for national risk index etl, still in progress
* Removes test_data from .gitignore
* Adds test data to nation_risk_index tests
* Creates tests and ETL class for NRI data
* Adds tests for load() and transform() methods of NationalRiskIndexETL
* Updates README.md with info about the NRI dataset
* Adds to dos
* Moves tests and test data into a tests/ dir in national_risk_index
* Moves tmp_dir for tests into data/tmp/tests/
* Promotes fixtures to conftest and relocates national_risk_index tests:
The relocation of national_risk_index tests is necessary because tests
can only use fixtures specified in conftests within the same package
* Fixes issue with df.equals() in test_transform()
* Files reformatted by black
* Commit changes to other files after re-running black
* Fixes unused import that caused lint checks to fail
* Moves tests/ directory to app root for data_pipeline
