Use LargeBinary to store serialized Action messages
Before raising this MR, consider whether the following are required, and complete if so:
- Unit tests
- Documentation update(s)
If not required, please explain in brief why not.
PostgreSQL's database driver decodes the serialized Action as unicode when storing it using String as the column, which results in data which can't usefully be re-encoded back to a serialized Action. This results in the Action message which is eventually sent to workers being empty.
This MR drops that column and recreates it using LargeBinary, a helper column type from SQLAlchemy which automatically uses the preferred type for storing binary data based on the database backend being used.
Run a test build using one of the docker-compose examples before and after applying this MR.