Toucan-connectors

Changed

- Athena: fix the parameter injection

Changed

- Base connector: Fixed pagination values (`total_rows` and `total_returned_rows`)
- Athena: Hacked pagination values in case not all results were fetched

Changed

- Mongo: removed `_id` column in response DataFrame.

Changed

- All connectors: removed werkzeug dependency.

Changed

- All connectors: Add support for an optional `db_name` parameter in the `get_model` method.
- MySQL: Use the provided `db_name` for discoverability when possible in `get_model`.
- MySQL: Simplify query for schema construction in order to be compatible with older versions
- Redshift: Add an option to disable TCP keep-alive (enabled by default).

Changed

- MySQL: Do not specify a database on discoverability-related functions (listing databases and describing table schemas).