bpo-39968: Fix a typo error in get_readline_state() (GH-19028)

Author: shihai1991

Modules/readline.c

@@ -87,7 +87,7 @@ typedef struct {
 } readlinestate;
 
 static inline readlinestate*
-get_readline_state(PyModule *module)
+get_readline_state(PyObject *module)
 {
  void *state = PyModule_GetState(module);
  assert(state != NULL);