chore(processors): mark processors._ProcessorOfCallable as final (#6)

Mark the `sghi.etl.commons.processors._ProcessorOfCallable` class as final.

Author: kennedykori

src/sghi/etl/commons/processors.py

@@ -161,6 +161,7 @@ def dispose(self) -> None:
         self._logger.info("Disposal complete.")
 
 
+@final
 class _ProcessorOfCallable(Processor[_RDT, _PDT], Generic[_RDT, _PDT]):
     __slots__ = ("_delegate_to", "_is_disposed", "_logger")