git push heroku master fails

[joshuaSmith2021]

Setting up a server for a school club, thanks so much for the tutorial! I just hit a simple issue, and I imagine there is a simple(ish) fix...

Everything goes well until the first git push heroku master. Then this happens:

$ heroku buildpacks:add heroku/jvm
$ heroku buildpacks:add jkutner/minecraft
$ heroku config:set NGROK_API_TOKEN="my_token"

$ git push heroku master
Counting objects: 3, done.
Writing objects: 100% (3/3), 229 bytes | 0 bytes/s, done.
Total 3 (delta 0), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote: 
remote: -----> App not compatible with buildpack: https://buildpack-registry.s3.amazonaws.com/buildpacks/heroku/python.tgz
remote:        More info: https://devcenter.heroku.com/articles/buildpacks#detection-failure
remote: 
remote:  !     Push failed
remote: Verifying deploy...
remote: 
remote: !       Push rejected to secret-forest-58202.
remote: 
To https://git.heroku.com/secret-forest-58202.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/secret-forest-58202.git'

Thanks!