github – Rails6 Heroku push error

git push is working fine only getting error when using git push heroku master
there is an error given below in image

enter image description here

my gem file:-

source ''
git_source(:github) { |repo| "{repo}.git" }

ruby '2.7.1'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '~> 6.0.3', '>='
# Use sqlite3 as the database for Active Record

# Use Puma as the app server
gem 'puma', '~> 4.1'
# Use SCSS for stylesheets
gem 'sass-rails', '>= 6'
# Transpile app-like JavaScript. Read more:
gem 'webpacker', '~> 4.0'
# Turbolinks makes navigating your web application faster. Read more:
gem 'turbolinks', '~> 5'
# Build JSON APIs with ease. Read more:
gem 'jbuilder', '~> 2.7'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 4.0'
# Use Active Model has_secure_password
# gem 'bcrypt', '~> 3.1.7'

# Use Active Storage variant
# gem 'image_processing', '~> 1.2'

# Reduces boot times through caching; required in config/boot.rb
gem 'bootsnap', '>= 1.4.2', require: false

group :development, :test do
  gem 'sqlite3', '~> 1.4'
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: (:mri, :mingw, :x64_mingw)

group :development do
  # Access an interactive console on exception pages or by calling 'console' anywhere in the     code.
 gem 'web-console', '>= 3.3.0'
 gem 'listen', '~> 3.2'
 # Spring speeds up development by keeping your application running in the background. Read more:
 gem 'spring'
 gem 'spring-watcher-listen', '~> 2.0.0'

group :test do
  # Adds support for Capybara system testing and selenium driver
  gem 'capybara', '>= 2.15'
  gem 'selenium-webdriver'
  # Easy installation and use of web drivers to run system tests with browsers
  gem 'webdrivers'

group :production do
  gem 'pg'
# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: (:mingw, :mswin, :x64_mingw, :jruby)