Fix broken test

Summary:
This test seems to be broken for at least a month and is blocking S343974
Specifically, the fbpkg builds are blocked by this:
https://www.internalfb.com/intern/sandcastle/job/27021598739017954

Reviewed By: gunchu

Differential Revision: D46848358

fbshipit-source-id: 4109c6bf909594dc42543a986e4c55398fcb2f07

Author: schwarzmx

multipy/runtime/example/examples.py

@@ -156,7 +156,7 @@ def forward(
         self, t: Tuple[Tensor, Tensor]
     ) -> Tuple[Tuple[Tensor, Tensor], Tuple[Tensor, Tensor]]:
         a, b = t
-        result = ((a.masked_fill_(b, 0.1), b), (torch.ones_like(a), b))
+        result = ((a.masked_fill_(b.to(torch.bool), 0.1), b), (torch.ones_like(a), b))
         return result