bpo-39573: Use Py_TYPE() macro in Objects directory (GH-18392)

Replace direct access to PyObject.ob_type with Py_TYPE().
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 5334eca..4edd93d 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -2762,7 +2762,7 @@
 
     PyErr_Format(PyExc_TypeError,
                  "cannot convert '%.200s' object to bytes",
-                 x->ob_type->tp_name);
+                 Py_TYPE(x)->tp_name);
     return NULL;
 }