Add pyre-ignore for Future instantiation in common.py and basic_models.py

Summary:
Pyre reports `Call error [29]: typing.Type[Future] is not a function` when instantiating `torch.futures.Future()` because the type stubs declare it as a generic type rather than a callable class.

Added `pyre-ignore[29]` comments to suppress these false positives since `Future` is callable at runtime. This affects:
- `_construct_future_forward` in common.py
- `BasicModel_MultiLayer_with_Future.forward` in basic_models.py

Differential Revision: D89870780

Author: Vivek Miglani

captum/_utils/common.py

@@ -574,6 +574,7 @@ def _format_outputs(
 # pyre-fixme[24] Callable requires 2 arguments
 def _construct_future_forward(original_forward: Callable) -> Callable:
     def future_forward(*args: Any, **kwargs: Any) -> torch.futures.Future[Tensor]:
+        # pyre-ignore[29]: `Future` is callable at runtime
         fut: torch.futures.Future[Tensor] = torch.futures.Future()
         fut.set_result(original_forward(*args, **kwargs))
         return fut

captum/testing/helpers/basic_models.py

@@ -581,6 +581,7 @@ def forward(
             self.relu(lin1_out)
         else:
             relu_out = self.relu(lin1_out)
+        # pyre-ignore[29]: `Future` is callable at runtime
         result = Future()
         lin2_out = self.linear2(relu_out)
         if multidim_output: