goal
I am very new to Heroku and I am trying to deploy a very simple site to Heroku.
Site structure

As you can see, I'm not trying to deploy a complex Node.js or Laravel Site here.
Actions
Of course, I enter the hero, then
cd idesign4u/ git init heroku git:remote -a idesign4u git add . git commit -am "Project Initialization" heroku buildpacks:set heroku/php
I got it
Buildpack set. Next release on idesign4u will use heroku/php. Run git push heroku master to create a new release using this buildpack.
I thought everything was set up. Then i ran
git push heroku master
Result
I kept getting
Counting objects: 67, done. Delta compression using up to 4 threads. Compressing objects: 100% (64/64), done. Writing objects: 100% (67/67), 60.75 MiB | 6.16 MiB/s, done. Total 67 (delta 2), reused 0 (delta 0) remote: Compressing source files... done. remote: Building source: remote: remote: -----> Failed to detect set buildpack https://codon-buildpacks.s3.amazonaws.com/buildpacks/heroku/php.tgz remote: More info: https://devcenter.heroku.com/articles/buildpacks
Could not find set buildpack https://codon-buildpacks.s3.amazonaws.com/buildpacks/heroku/php.tgz
Questions
How do I get around this?
Are there any other settings I need to make on the Heroku website?
How would I do this and debug it further?
I open any offers at this moment.
Any tips / suggestions / help on this would be greatly appreciated!
Note
I found here a SO post like this:
Click rejected, could not detect set buildpack heroku / php
I looked at him, but in my case this is not very important.