Fix a bug in temporal shortcut (#20)

Temporal tensors are 5D, including a temporal axis at axis=1

Author: JihongJu

keras_resnet/block/temporal.py

@@ -98,8 +98,8 @@ def f(x):
 
 
 def _shortcut(a, b):
-    a_shape = keras.backend.int_shape(a)
-    b_shape = keras.backend.int_shape(b)
+    a_shape = keras.backend.int_shape(a)[1:]
+    b_shape = keras.backend.int_shape(b)[1:]
 
     if keras.backend.image_data_format() == "channels_last":
         x = int(round(a_shape[1] // b_shape[1]))