fix: add x_o ConditionalPotential __call__

sbi/utils/conditional_density_utils.py

@@ -294,12 +294,16 @@ def __init__(
         self.device = self.potential_fn.device
         self.allow_iid_x = allow_iid_x
 
-    def __call__(self, theta: Tensor, track_gradients: bool = True) -> Tensor:
+    def __call__(
+        self, theta: Tensor, x_o: Tensor, track_gradients: bool = True
+    ) -> Tensor:
         r"""
         Returns the conditional potential $\log(p(\theta_i|\theta_j, x))$.
 
         Args:
             theta: Free parameters $\theta_i$, batch dimension 1.
+            x_o: Observed data $x$.
+            track_gradients: Whether to track gradients.
 
         Returns:
             Conditional posterior log-probability $\log(p(\theta_i|\theta_j, x))$,