Add .env.example file.

Add running with docker compose.

Merge pull request #3 from LUS24/leospairani/cou-300-section-12-lecture-121-video-ebook-code-mismatch

Updated according to COU-300

feat(unique): make tag names non-unique

feat(html email): add html version of registration email

build: use REDIS_URL instead of RENDER_REDIS_URL

tests(register): update testing to include email

build(gh): pass environment secrets as env vars in workflow

build(gh): update workflow to use environment

feat(rq): add settings file for workers

deps(requests): add missing requests library

feat(task queues): add rq task queue for sending user registration email

deprecation(flask): Remove before_first_request

bug(schema): fix schema issues in SQLAlchemy models