bpo-33012: Fix invalid function cast warnings with gcc 8 for METH_NOARGS. (GH-6030)

METH_NOARGS functions need only a single argument but they are cast
into a PyCFunction, which takes two arguments.  This triggers an
invalid function cast warning in gcc8 due to the argument mismatch.
Fix this by adding a dummy unused argument.

Modules/_sqlite/row.c

@@ -155,7 +155,7 @@ Py_ssize_t pysqlite_row_length(pysqlite_Row* self, PyObject* args, PyObject* kwa
     return PyTuple_GET_SIZE(self->data);
 }
 
-PyObject* pysqlite_row_keys(pysqlite_Row* self, PyObject* args, PyObject* kwargs)
+PyObject* pysqlite_row_keys(pysqlite_Row* self, PyObject *Py_UNUSED(ignored))
 {
     PyObject* list;
     Py_ssize_t nitems, i;