No valid/supported repository was found at the given URL

[GO3LIN]

Hello,

I created a plugin to let users configure the imap server parameters at login page. And I want to share it with the community. However, when I try to submit it, it just gave me the error "No valid/supported repository was found at the given URL". I have created a composer.json as marked but still don't know what's the problem. Here's the plugin url : https://github.com/go3lin/other_server

Thanks