bpo-30459: Cast the result of PyList_SET_ITEM() to void (GH-19975)

Do the same for PyTuple_SET_ITEM().
diff --git a/Include/cpython/tupleobject.h b/Include/cpython/tupleobject.h
index 51dcd42..7cada88 100644
--- a/Include/cpython/tupleobject.h
+++ b/Include/cpython/tupleobject.h
@@ -23,6 +23,6 @@ PyAPI_FUNC(void) _PyTuple_MaybeUntrack(PyObject *);
 #define PyTuple_GET_ITEM(op, i) (_PyTuple_CAST(op)->ob_item[i])
 
 /* Macro, *only* to be used to fill in brand new tuples */
-#define PyTuple_SET_ITEM(op, i, v) (_PyTuple_CAST(op)->ob_item[i] = v)
+#define PyTuple_SET_ITEM(op, i, v) ((void)(_PyTuple_CAST(op)->ob_item[i] = v))
 
 PyAPI_FUNC(void) _PyTuple_DebugMallocStats(FILE *out);