Upgrade ubuntu image

Bump pytest-mock from 3.5.1 to 3.6.1

Set up security scanning

Upgrade to GitHub-native Dependabot

Bump pytest from 6.2.2 to 6.2.3

Bump cryptography from 3.3.2 to 3.4.7

Bump alembic from 1.5.3 to 1.5.8

Bump flake8 from 3.8.4 to 3.9.0

Bump flask-migrate from 2.6.0 to 2.7.0 (#441)

[Security] Bump jinja2 from 2.11.2 to 2.11.3

[Security] Bump cryptography from 3.3.1 to 3.3.2

Bump alembic from 1.4.3 to 1.5.3

Bump pyyaml from 5.3.1 to 5.4.1

Bump flask-migrate from 2.5.3 to 2.6.0

Bump pyjwt from 2.0.0 to 2.0.1