chore: add return type hint

Co-authored-by: Robert Bartel <[email protected]>

python/ngen_cal/src/ngen/cal/_optimizers/grey_wolf.py

@@ -124,7 +124,7 @@ def optimize(
         n_processes: Optional[int] = None,
         verbose: bool = True,
         **kwargs,
-    ):
+    ) -> Tuple[float, np.ndarray]:
         """Optimize the swarm for a number of iterations
 
         Performs the optimization to evaluate the objective