我对独库很陌生。我在 DigitalOcean 设置了一个新的 dokku droplet。我创建了一个小型静态网站，其 www 目录包含一个名为 index.html 的 HTML 文件。在根目录中，我添加了一个空的 .nginx 文件。当我尝试推送时，我得到以下输出：
Counting objects: 5, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (5/5), 356 bytes | 0 bytes/s, done.
Total 5 (delta 0), reused 0 (delta 0)
-----> Cleaning up ...
remote: Cloning into '/tmp/tmp.FFdk4jjPhW'...
-----> Building dokkutest ...
remote: warning: You appear to have cloned an empty repository.
remote: done.
remote: HEAD is now at 0046a12... First implementation
-----> Unable to select a buildpack
To dokku@123.123.123.123:dokkutest
! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'dokku@123.123.123.123:dokkutest'
关于我可能做错了什么的任何想法？