remove unnecessary scaling from mock dataset

mu_map/dataset/mock.py

@@ -11,7 +11,7 @@ class MuMapMockDataset(MuMapDataset):
         recon, mu_map = super().__getitem__(0)
         recon = recon[:, :32, :, :]
         mu_map = mu_map[:, :32, :, :]
-        return recon, mu_map / 40206.0
+        return recon, mu_map
 
     def __len__(self):
         return self.len