Update "first_conv" in config.json

Filled "first_conv" in config.json for a model to correctly change input channel number.

config.json

@@ -30,7 +30,7 @@
       8,
       8
     ],
-    "first_conv": null,
+    "first_conv": ["stem.0.conv_scale.conv", "stem.0.conv_kxk.0.conv"],
     "classifier": "head.fc"
   }
 }