Fix typo

ml-agents/mlagents/trainers/torch/distributions.py

             )
 
     def forward(self, inputs: torch.Tensor, goal: torch.Tensor):
-        mu = self.mu(inputs, goal)
+        mu = self.hypernet(inputs, goal)
         if self.conditional_sigma:
             log_sigma = torch.clamp(self.log_sigma(inputs), min=-20, max=2)
         else: