adding IntpHashTable to hashtable.pyi

Author: realead

pandas/_libs/hashtable.pyi

@@ -197,6 +197,7 @@ class UInt16HashTable(HashTable): ...
 class UInt8HashTable(HashTable): ...
 class StringHashTable(HashTable): ...
 class PyObjectHashTable(HashTable): ...
+class IntpHashTable(HashTable): ...
 
 def duplicated_int64(
     values: np.ndarray,  # const int64_t[:] values