update default batch size for cgan training

mu_map/training/cgan.py

@@ -304,7 +304,7 @@ if __name__ == "__main__":
     parser.add_argument(
         "--batch_size",
         type=int,
-        default=8,
+        default=64,
         help="the batch size used for training",
     )
     parser.add_argument(