Mark readline module in no-gil builds.

This means: "Do not re-enable the GIL when importing rl.readline."

See python/cpython#116322
See python/cpython#116882

Author: stefanholek

rl/readline.c

@@ -3600,6 +3600,11 @@ PyInit_readline(void)
 	if (m == NULL)
 		return NULL;
 
+#ifdef Py_GIL_DISABLED
+	/* Cargo-culted from Modules/readline.c
+	   This means: "Do not re-enable the GIL when importing rl.readline." */ 
+	PyUnstable_Module_SetGIL(m, Py_MOD_GIL_NOT_USED);
+#endif
 	PyOS_ReadlineFunctionPointer = call_readline;
 
 	if (setup_readline(m) < 0) {