I have a Django project and I was trying for the first time to deploy in the Heroku cloud. The project structure is as following,

# Project structure:

.\Project folder\ -
                |
                |- .\env\ (Virtual enviroment )
                |
                |- .\src\ -
                |          |
                |          |- .\main\ -
                |          |           |
                |          |           |- admin.py  (Output tables data in to admin dashboard)
                |          |           |- models.py (Classes os DB tables)
                |          |           |- serializers.py (Serializing of data output in API)
                |          |           |- views.py (Custome API views)
                |          |           |- ...
                |          |
                |          |- .\users_groups\ -
                |          |                   |
                |          |                   |- settings.py (Project settings)
                |          |                   |- urls.py ( file with URL's reg. ex. patterns)
                |          |                   |- wsgi.py
                |          |
                |          |- .\templates\ 
                |          |
                |          |- manage.py
                |          |- db.sqlite3
                |
                |- .\app-messages
                |
                |- ReadMe.txt 
                |
                |- requirements.txt (file with list of all dependencies for app)

My project is here and I followed this tutorial. I was inside the .\Project folder\ and at the time of pushing in the master, I get some error. I use the command to push,

git push heroku master

I get the error message,

To https://git.heroku.com/i2x-team-app.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/i2x-team-app.git'

What should I do to solve this issue?