CLN: Remove Categorical.itemsize

Author: Terji Petersen

pandas/core/arrays/categorical.py

@@ -561,13 +561,6 @@ def astype(self, dtype: AstypeArg, copy: bool = True) -> ArrayLike:
 
         return result
 
-    @cache_readonly
-    def itemsize(self) -> int:
-        """
-        return the size of a single category
-        """
-        return self.categories.itemsize
-
     def to_list(self):
         """
         Alias for tolist.