Fix type checks for EnsemblePosterior weights (#1299)

* minor fix for EnsemblePosterior weights.setter

* Update sbi/inference/posteriors/ensemble_posterior.py

Co-authored-by: Jan <janfb@users.noreply.github.com>

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Co-authored-by: Jan <janfb@users.noreply.github.com>

Author: CompiledAtBirth

sbi/inference/posteriors/ensemble_posterior.py

@@ -137,7 +137,7 @@ def weights(self, weights: Optional[Union[List[float], Tensor]]) -> None:
             self._weights = torch.tensor([
                 1.0 / self.num_components for _ in range(self.num_components)
             ])
-        elif weights is Tensor or weights is List:
+        elif isinstance(weights, (Tensor, List)):
             self._weights = torch.tensor(weights) / sum(weights)
         else:
             raise TypeError