Fix NormalSimulator output shapes

Author: han-ol

tests/utils/normal_simulator.py

@@ -17,6 +17,9 @@ def sample(self, batch_shape: Shape, num_observations: int = 32) -> dict[str, Te
         noise = np.random.standard_normal(batch_shape + (num_observations, 2))
 
         x = mean + std * noise
+        x = x.reshape(x.shape[0], -1)
+        mean = mean[:, 0]
+        std = std[:, 0]
         mean = mean.astype("float32")
         std = std.astype("float32")
         x = x.astype("float32")