heroku openでブラウザ開きません。

git mergeで難しいnanoからvimに変更し、README.mdは無事変更できました。ありがとうございます。
次は　herokuをpushしてopenができません。過去の掲示板でかかれてあったhttps://●●●●-10111.herokuapp.comや
https://●●●●-10111.herokuapp.com/index.phpでもブラウザは真っ白です。
pushで問題があればご教授下さい。宜しくお願い致します。

leimond:~/environment (master) $ git push heroku master
Counting objects: 18, done.
Compressing objects: 100% (11/11), done.
Writing objects: 100% (18/18), 2.69 KiB | 688.00 KiB/s, done.
Total 18 (delta 6), reused 11 (delta 2)
remote: Compressing source files... done.
remote: Building source:
remote: 
remote: -----> PHP app detected
remote: 
remote:  !     WARNING: No 'composer.json' found!
remote:  !     
remote:  !     Your project only contains an 'index.php', no 'composer.json'.
remote:  !     
remote:  !     Using 'index.php' to declare app type as PHP is deprecated and
remote:  !     may lead to unexpected behavior.
remote:  !     
remote:  !     Please consider updating your codebase to utilize Composer and
remote:  !     modern dependency management in order to benefit from the latest
remote:  !     PHP runtimes and improved application performance, as well as
remote:  !     control over the PHP versions and extensions available.
remote:  !     
remote:  !     For an introduction to dependency management with Composer and
remote:  !     how to get the most out of PHP on Heroku, refer to the docs at
remote:  !     https://getcomposer.org/doc/00-intro.md and
remote:  !     https://devcenter.heroku.com/articles/getting-started-with-php
remote: 
remote: -----> Bootstrapping...
remote: -----> Installing platform packages...
remote:        NOTICE: No runtime required in composer.lock; using PHP ^5.5.17
remote:        - nginx (1.8.1)
remote:        - php (5.6.37)
remote:        - apache (2.4.34)
remote: -----> Installing dependencies...
remote:        Composer version 1.7.2 2018-08-16 16:57:12
remote: -----> Preparing runtime environment...
remote:        NOTICE: No Procfile, using 'web: heroku-php-apache2'.
remote: -----> Checking for additional extensions to install...
remote: -----> Discovering process types
remote:        Procfile declares types -> web
remote: 
remote: -----> Compressing...
remote:        Done: 37.6M
remote: -----> Launching...
remote:        Released v6
remote:        https://●●●●.herokuapp.com/ deployed to Heroku
remote: 
remote: Verifying deploy... done.
To https://git.heroku.com/●●●●-10111.git
   b76863d6..d3fd4fe0  master -> master
leimond:~/environment (master) $ heroku open
 ▸    Error opening web browser.
 ▸    Error: Exited with code 3
 ▸    
 ▸    Manually visit https://●●●●-10111.herokuapp.com/ in your browser.