Authsign

Updating type annotations, dependencies, and update to latest testing tools. No code changes.

What's Changed
* Add type annotation to SignedHash model by tw4l in https://github.com/webrecorder/authsign/pull/5

New Contributors
* tw4l made their first contribution in https://github.com/webrecorder/authsign/pull/5

**Full Changelog**: https://github.com/webrecorder/authsign/compare/0.5.0...0.5.1

Improvements include:
- concurrency: always run with only 1 work in default run script and in Dockerfile
- timestamp check: ensure the 'created' timestamp is no newer than signed timestamp and no older than duration, not other way way around
- typing: set model to use datetime for signed request and signed hash, use dateutil for more accepting parsing
- invalid datetime now results in 422 response, not 400
- linting: add pylint testing, add missing docstrings, ignore extraneous warnings

Slightly improved error handling:
- print full stack trace of certificate get error
- avoid extraneous exception thrown due to None object, caused by real exception (certificate get error).

Sets the default certificate validity to 7 days instead of 48 hours.
Also allow configuring the certificate validity duration and timestamp signing duration in the config (defaulting to 7 days and 10 mins, respectively).

Initial automated release
- Add Dockerfile and automated docker build
- Update logging for signing and verification server (don't print token, print certificate fingerprint)