Adds National Risk Index data to ETL pipeline (#549)

* 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

data/data-pipeline/data_pipeline/etl/constants.py

@@ -39,6 +39,11 @@ DATASET_LIST = [
         "module_dir": "cdc_places",
         "class_name": "CDCPlacesETL",
     },
+    {
+        "name": "national_risk_index",
+        "module_dir": "national_risk_index",
+        "class_name": "NationalRiskIndexETL",
+    },
 ]
 CENSUS_INFO = {
     "name": "census",