capybara-webkitがインストールできず、bundleが通らない

railsでアプリケーション構築を行っています。
rbenvでgemsetを作成し直したところ、bundleが通らなくなりました。

原因はcapybara-webkitがインストールできないからというところで試行錯誤しているところです。
原因が特定できずおります、どなたかアドバイスいただけますと幸いでございます。

実行環境
・mojave
・ruby 2.5.3
・rails 5.1
・postgres 10.1

bundle install

Fetching capybara-webkit 1.15.1
Installing capybara-webkit 1.15.1 with native extensions
Errno::EACCES: Permission denied @ rb_sysopen - /Users/user_name/.rbenv/versions/2.5.3/gemsets/gem-name/gems/capybara-webkit-1.15.1/.gitignore
An error occurred while installing capybara-webkit (1.15.1), and Bundler cannot continue.
Make sure that `gem install capybara-webkit -v '1.15.1' --source 'https://rubygems.org/'` succeeds before bundling.

In Gemfile:
  capybara-webkit

実行コード
$ sudo gem install capybara-webkit -v '1.15.1' --source 'https://rubygems.org/'

Password:
Building native extensions. This could take a while...
ERROR:  Error installing capybara-webkit:
	ERROR: Failed to build gem native extension.

    current directory: /Users/user_name/.rbenv/versions/2.5.3/gemsets/gem-name/gems/capybara-webkit-1.15.1
/Users/user_name/.rbenv/versions/2.5.3/bin/ruby -r ./siteconf20181127-29269-1wqpkb0.rb extconf.rb
Info: creating stash file /Users/user_name/.rbenv/versions/2.5.3/gemsets/gem-name/gems/capybara-webkit-1.15.1/.qmake.stash
cd src/ && ( test -e Makefile.webkit_server || /usr/local/opt/qt/bin/qmake -o Makefile.webkit_server /Users/user_name/.rbenv/versions/2.5.3/gemsets/gem-name/gems/capybara-webkit-1.15.1/src/webkit_server.pro ) && /Applications/Xcode.app/Contents/Developer/usr/bin/make -f Makefile.webkit_server
Project ERROR: No QtWebKit installation found. QtWebKit is no longer included with Qt 5.6, so you may need to install it separately.
make: *** [sub-src-webkit_server-pro-make_first-ordered] Error 3
Command 'make  --jobs=4' failed

current directory: /Users/user_name/.rbenv/versions/2.5.3/gemsets/gem-name/gems/capybara-webkit-1.15.1
make "DESTDIR=" clean
cd src/ && ( test -e Makefile.webkit_server || /usr/local/opt/qt/bin/qmake -o Makefile.webkit_server /Users/user_name/.rbenv/versions/2.5.3/gemsets/gem-name/gems/capybara-webkit-1.15.1/src/webkit_server.pro ) && /Applications/Xcode.app/Contents/Developer/usr/bin/make -f Makefile.webkit_server clean
Project ERROR: No QtWebKit installation found. QtWebKit is no longer included with Qt 5.6, so you may need to install it separately.
make: *** [sub-src-webkit_server-pro-clean-ordered] Error 3

current directory: /Users/user_name/.rbenv/versions/2.5.3/gemsets/gem-name/gems/capybara-webkit-1.15.1
make "DESTDIR="
cd src/ && ( test -e Makefile.webkit_server || /usr/local/opt/qt/bin/qmake -o Makefile.webkit_server /Users/user_name/.rbenv/versions/2.5.3/gemsets/gem-name/gems/capybara-webkit-1.15.1/src/webkit_server.pro ) && /Applications/Xcode.app/Contents/Developer/usr/bin/make -f Makefile.webkit_server
Project ERROR: No QtWebKit installation found. QtWebKit is no longer included with Qt 5.6, so you may need to install it separately.
make: *** [sub-src-webkit_server-pro-make_first-ordered] Error 3

make failed, exit code 2

Gem files will remain installed in /Users/user_name/.rbenv/versions/2.5.3/gemsets/gem-name/gems/capybara-webkit-1.15.1 for inspection.
Results logged to /Users/user_name/.rbenv/versions/2.5.3/gemsets/gem-name/extensions/x86_64-darwin-18/2.5.0-static/capybara-webkit-1.15.1/gem_make.out

### 追記

$ brew extract --help
Look through repository history to find the most recent version of formula and
create a copy in tap/Formula/formula@version.rb. If the tap is not
installed yet, attempt to install/clone the tap before continuing.

        --version                    Extract the provided version of formula
                                     instead of the most recent.
    -f, --force                      Override warnings and enable potentially
                                     unsafe operations.
    -d, --debug                      Display any debugging information.
    -h, --help                       Show this message.