Ruby on Rails6　heroku用のGemをインストールしたい

前提・実現したいこと

Ruby on Railsにてブログアプリを作成しました
HerokuにてRailsアプリを公開したい
公開方法なは下記のリンクを参考にしました。
リンク内容

発生している問題・エラーメッセージ

リンクを参考に

gem
1コード
2gem 'sqlite3', group: :development
3gem 'pg', group: :production

と記述しbundle installを実行しました。

  current directory: /Users/kojin/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/pg-1.2.3/ext
/Users/kojin/.rbenv/versions/2.5.1/bin/ruby -I /Users/kojin/.rbenv/versions/2.5.1/lib/ruby/site_ruby/2.5.0 -r ./siteconf20201117-19482-jon8rf.rb extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/Users/kojin/.rbenv/versions/2.5.1/bin/$(RUBY_BASE_NAME)
	--with-pg
	--without-pg
	--enable-windows-cross
	--disable-windows-cross
	--with-pg-config
	--without-pg-config
	--with-pg_config
	--without-pg_config
	--with-pg-dir
	--without-pg-dir
	--with-pg-include
	--without-pg-include=${pg-dir}/include
	--with-pg-lib
	--without-pg-lib=${pg-dir}/lib

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /Users?kojin/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/extensions/x86_64-darwin-19/2.5.0/pg-1.2.3/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /Users/kojin/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/pg-1.2.3 for inspection.
Results logged to /Users/kojin/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/extensions/x86_64-darwin-19/2.5.0/pg-1.2.3/gem_make.out

An error occurred while installing pg (1.2.3), and Bundler cannot continue.
Make sure that `gem install pg -v '1.2.3' --source 'https://rubygems.org/'` succeeds before bundling.

該当するソースコード

gem
1
2ruby '2.5.1'
3
4# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
5gem 'rails', '~> 6.0.3', '>= 6.0.3.4'
6# Use sqlite3 as the database for Active Record
7gem 'sqlite3', '~> 1.4', group: :development
8gem 'pg', group: :production
9# Use Puma as the app server
10gem 'puma', '~> 4.1'
11# Use SCSS for stylesheets
12gem 'sass-rails', '>= 6'
13# Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker
14gem 'webpacker', '~> 4.0'
15# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
16gem 'turbolinks', '~> 5'
17# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
18gem 'jbuilder', '~> 2.7'
19# Use Redis adapter to run Action Cable in production
20# gem 'redis', '~> 4.0'
21# Use Active Model has_secure_password
22# gem 'bcrypt', '~> 3.1.7'
23
24# Use Active Storage variant
25# gem 'image_processing', '~> 1.2'
26
27# Reduces boot times through caching; required in config/boot.rb
28gem 'bootsnap', '>= 1.4.2', require: false
29
30group :development, :test do
31  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
32  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
33end
34
35group :development do
36  # Access an interactive console on exception pages or by calling 'console' anywhere in the code.
37  gem 'web-console', '>= 3.3.0'
38  gem 'listen', '~> 3.2'
39  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
40  gem 'spring'
41  gem 'spring-watcher-listen', '~> 2.0.0'
42end
43
44group :test do
45  # Adds support for Capybara system testing and selenium driver
46  gem 'capybara', '>= 2.15'
47  gem 'selenium-webdriver'
48  # Easy installation and use of web drivers to run system tests with browsers
49  gem 'webdrivers'
50end
51
52# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
53gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
54gem 'actiontext'
55gem 'image_processing', '~> 1.2'
56gem 'haml-rails'
57gem 'bourbon'
58gem 'devise'
59gem 'jquery-rails'
60gem 'font-awesome-sass'