Migrate bill topic assignment to pipeline

[jessiclassy]

Currently, bill topic assignment lives in legislation-tracker/db/db-population. Ideally, it can be migrated to the pipeline.py job. Dependencies like topic_keywords.yaml should be migrated to the common db package as well, in a child folder called resources or something similar. NB: web app references the topic keys on the bills page which will need to be update

[jessiclassy]

BUNDLE WITH THIS: update NLP package requirements to resolve security alerts