#3521 refactor: Make the base `Target` class generic on its associated `Sink` class Pull request opened by edgarrmondragon SSIA Summary by Sourcery Make the base Target class generic over its associated Sink type and tighten sink typing for SQL targets. Enhancements: • Parameterize the Target base class with a generic Sink type and update related attributes and methods to use the generic type. • Refine SQLTarget sink-related method type hints to use SQLSink instead of the generic Sink. • Improve type-checking support by adding typing-only dependencies for datetime ISO parsing and importlib metadata. meltano/sdk