move process.stdin.unref call inside setupHistory callback

Author: dario-piotrowicz

test/parallel/test-repl-no-terminal.js

@@ -3,5 +3,6 @@ const common = require('../common');
 
 const repl = require('repl');
 const r = repl.start({ terminal: false });
-r.setupHistory('/nonexistent/file', common.mustSucceed());
-process.stdin.unref?.();
+r.setupHistory('/nonexistent/file', common.mustSucceed(() => {
+    process.stdin.unref?.();
+}));