在Heroku尝试更新，失败了

[linkingjj]

-----> Building on the Heroku-20 stack
-----> Determining which buildpack to use for this app
! No default language could be detected for this app.
HINT: This occurs when Heroku cannot detect the buildpack to use for this application automatically.
See https://devcenter.heroku.com/articles/buildpacks
! Push failed