Bug: missing `DiffusionActiveInference` object attribute `self.epistemic_optimizer`

[jeipollack]

When testing deployment, I encountered this AttributeError:

AttributeError: 'DiffusionActiveInference' object has no attribute 'epistemic_optimizer'

Right after setting, self.epistemic_estimator, I added the line:

+        self.epistemic_optimizer = torch.optim.Adam(
+            self.epistemic_estimator.parameters(),
+            lr=self.config.epistemic_lr if hasattr(self.config, "epistemic_lr") else 1e-4
+        )

And re-deployed.