Erro ao rodar git push

Enumerating objects: 110, done.
Counting objects: 100% (110/110), done.
Delta compression using up to 8 threads
Compressing objects: 100% (93/93), done.
Writing objects: 100% (110/110), 902.01 KiB | 7.33 MiB/s, done.
Total 110 (delta 8), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote:
remote:  !     No default language could be detected for this app.
remote:                         HINT: This occurs when Heroku cannot detect the buildpack to use for this application automatically.
remote:                         See https://devcenter.heroku.com/articles/buildpacks
remote:
remote:  !     Push failed
remote: Verifying deploy...
remote:
remote: !       Push rejected to cdcspringmvc-rodrigo2rpa-alura.
remote:
To https://git.heroku.com/cdcspringmvc-rodrigo2rpa-alura.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/cdcspringmvc-rodrigo2rpa-alura.git'