Added type hint None to specify_shape()

Author: sudarsan2k5

aesara/tensor/shape.py

@@ -542,7 +542,7 @@ def c_code_cache_version(self):
 def specify_shape(
     x: Union[np.ndarray, Number, Variable],
     shape: Union[
-        int, List[Union[int, Variable]], Tuple[Union[int, Variable]], Variable
+        int, List[Union[int, None, Variable]], Tuple[Union[int, None, Variable]], Variable
     ],
 ):
     """Specify a fixed shape for a `Variable`.