Python 3.8 support.

More flexible json logger and black/isort.

Django, Python deprecations. Sanic support. Minor fixes.

Minor fix for sqlalchemy and Flask.

Backward-compat fix for Flask migration check.

Doc and logging fixes.

Flask support and minor fixes.

Fixed mozlog message field name to match spec.

Logging docs fixes, speed and compat improvements.

Minor fix to JSON serialization.