Address review: visit node->key, node->data, and con->isolation_level

Author: Erlend E. Aasland

Modules/_sqlite/cache.c

@@ -47,6 +47,8 @@ pysqlite_new_node(PyObject *key, PyObject *data)
 static int
 node_traverse(pysqlite_Node *self, visitproc visit, void *arg)
 {
+    Py_VISIT(self->key);
+    Py_VISIT(self->data);
     Py_VISIT(Py_TYPE(self));
     return 0;
 }

Modules/_sqlite/connection.c

@@ -229,6 +229,7 @@ static int
 connection_traverse(pysqlite_Connection *self, visitproc visit, void *arg)
 {
     Py_VISIT(self->statement_cache);
+    Py_VISIT(self->isolation_level);
     Py_VISIT(self->function_pinboard_trace_callback);
     Py_VISIT(self->function_pinboard_progress_handler);
     Py_VISIT(self->function_pinboard_authorizer_cb);