bpo-39573: Clean up modules and headers to use Py_IS_TYPE() function (GH-18521)

diff --git a/Modules/_csv.c b/Modules/_csv.c
index 4243772..f820f55 100644
--- a/Modules/_csv.c
+++ b/Modules/_csv.c
@@ -106,7 +106,7 @@
 
 static PyTypeObject Reader_Type;
 
-#define ReaderObject_Check(v)   (Py_TYPE(v) == &Reader_Type)
+#define ReaderObject_Check(v)   Py_IS_TYPE(v, &Reader_Type)
 
 typedef struct {
     PyObject_HEAD