Opstrich

Changed
- Upgraded poetry to 1.1.4
- Bumped invoke from 1.4.1 to 1.5.0
- Bumped isort from 5.6.4 to 5.7.0
- Bumped pyupgrade from 2.7.4 to 2.9.0

Added
- `package.bump` invoke task to bump the version of a package, then commit, tag, and push the updated version

Added
- Initial `check` invoke tasks including `pyupgrade`, `isort`, `black`, `migrations`, and `all` (which runs all of the checks)
- `openssl` invoke tasks `encrypt` and `decrypt` for encrypting/decrypting files using `DECRYPT_PASSWORD`
- Python 3.8 support
- `Dockerfile` used as parent for Zappa projects using SQLite