Created migration mode in app

[JoshD94]

Overview

Created a migration mode in app.py which is activated by setting the environment variable FLASK_MIGRATE to true

Changes Made

• Wrapped imports and scrapers in condition, only run when FLASK_MIGRATE environment variable is set to false or is not set
• Changed workflow file to set FLASK_MIGRATE to true before migrating, and then setting to false afterwards
• Added FLASK_MIGRATE=false in Dockerfile to ensure no migrations occur during docker build

Test Coverage

Tested locally

Related PRs or Issues (delete if not applicable)

#169