$bundle installを実行したところpermission deniedとなりgemをインストールできません。
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エラー内容

The dependency tzinfo-data (>= 0) will be unused by any of the platforms Bundler is installing for. Bundler is installing for ruby but the dependency is only for x86-mingw32, x86-mswin32, x64-mingw32, java. To add those platforms to the bundle, run `bundle lock --add-platform x86-mingw32 x86-mswin32 x64-mingw32 java`.
Fetching gem metadata from https://rubygems.org/............
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies.....
Using rake 13.0.1
Using concurrent-ruby 1.1.5
Using i18n 1.7.0
Using minitest 5.13.0
Using thread_safe 0.3.6
Using tzinfo 1.2.5
Using activesupport 5.2.3
Using builder 3.2.3
Using erubi 1.9.0
Using mini_portile2 2.4.0
Fetching nokogiri 1.10.5
Errno::EACCES: Permission denied @ rb_file_s_rename -
(/Users/username/.gem/ruby/2.6.0/cache/nokogiri-1.10.5.gem,
/Users/username/rails/taskleaf/vendor/bundle/ruby/2.6.0/cache/nokogiri-1.10.5.gem)
An error occurred while installing nokogiri (1.10.5), and Bundler cannot continue.
Make sure that `gem install nokogiri -v '1.10.5' --source 'https://rubygems.org/'` succeeds before
bundling.

In Gemfile:
  rails was resolved to 5.2.3, which depends on
    actioncable was resolved to 5.2.3, which depends on
      actionpack was resolved to 5.2.3, which depends on
        actionview was resolved to 5.2.3, which depends on
          rails-dom-testing was resolved to 2.0.3, which depends on
            nokogiri

エラーメッセージの記載通り、
gem install nokogiri -v '1.10.5' --source 'https://rubygems.org/'を実行するもコマンド自体動きませんでした。

(https://rubygems.org/gems/nokogiri)　にて「nokogiri」を検索　
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gem 'nokogiri', '~> 1.10', '>= 1.10.5’をGemfileに貼り付け
$ gem install nokogiri　実行
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Permission denied @ rb_sysopen - /Users/username/.rbenv/versions/2.6.3/lib/ruby/gems/2.6.0/gems/nokogiri-1.10.5/LICENSE-DEPENDENCIES.md