patch 9.1.1472: if_python: PySequence_Fast_{GET_SIZE,GET_ITEM} removed

Problem:  if_python: PySequence_Fast_{GET_SIZE,GET_ITEM} removed with
          python3.14 in stable ABI
Solution: use PySequence_{Size,GetItem} instead (Zdenek Dohnal)

Python 3.14 removed those two functions from stable API because of
reasoning these function shouldn't be part of stable API at the first
place.

Moving to PySequence_GetSize and PySequence_GetItem fixes the build
failure when Vim is built with dynamic Python and stable API for Python
3.8.

closes: #17575

Signed-off-by: Zdenek Dohnal <zdohnal@redhat.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/if_py_both.h b/src/if_py_both.h
index ed66254..7fc055d 100644
--- a/src/if_py_both.h
+++ b/src/if_py_both.h
@@ -2409,18 +2409,18 @@
 
 		Py_DECREF(item);
 
-		if (PySequence_Fast_GET_SIZE(fast) != 2)
+		if (PySequence_Size(fast) != 2)
 		{
 		    Py_DECREF(iterator);
 		    Py_DECREF(fast);
 		    PyErr_FORMAT(PyExc_ValueError,
 			    N_("expected sequence element of size 2, "
 			    "but got sequence of size %d"),
-			    (int) PySequence_Fast_GET_SIZE(fast));
+			    (int) PySequence_Size(fast));
 		    return NULL;
 		}
 
-		keyObject = PySequence_Fast_GET_ITEM(fast, 0);
+		keyObject = PySequence_GetItem(fast, 0);
 
 		if (!(key = StringToChars(keyObject, &todecref)))
 		{
@@ -2442,7 +2442,7 @@
 		}
 		di->di_tv.v_type = VAR_UNKNOWN;
 
-		valObject = PySequence_Fast_GET_ITEM(fast, 1);
+		valObject = PySequence_GetItem(fast, 1);
 
 		if (ConvertFromPyObject(valObject, &di->di_tv) == -1)
 		{