我是Ruby的新手，我需要克隆一个现有的项目。
说明如下：

source .env.development
bundle install

但它失败的原因是：

Using libv8 3.16.14.15
Fetching libxml-ruby 2.9.0
Installing libxml-ruby 2.9.0 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

current directory: /Users/vlad/.rvm/gems/ruby-2.3.1/gems/libxml-ruby-2.9.0/ext/libxml
/Users/vlad/.rvm/rubies/ruby-2.3.1/bin/ruby -r ./siteconf20181109-46682-fvgifh.rb extconf.rb --use-system-libraries
checking for libxml/xmlversion.h in /opt/include/libxml2,/opt/local/include/libxml2,/usr/local/include/libxml2,/usr/include/libxml2... no

***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
--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/vlad/.rvm/rubies/ruby-2.3.1/bin/$(RUBY_BASE_NAME)
--with-xml2-config
--without-xml2-config
--with-xml2-dir
--without-xml2-dir
--with-xml2-include
--without-xml2-include=${xml2-dir}/include
--with-xml2-lib
--without-xml2-lib=${xml2-dir}/lib
 extconf failure: need libxml2.

    Install the library or try one of the following options to extconf.rb:

      --with-xml2-config=/path/to/xml2-config
      --with-xml2-dir=/path/to/libxml2
      --with-xml2-lib=/path/to/libxml2/lib
      --with-xml2-include=/path/to/libxml2/include

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

  /Users/vlad/.rvm/gems/ruby-2.3.1/extensions/x86_64-darwin-18/2.3.0/libxml-ruby-2.9.0/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /Users/vlad/.rvm/gems/ruby-2.3.1/gems/libxml-ruby-2.9.0 for inspection.
Results logged to /Users/vlad/.rvm/gems/ruby-2.3.1/extensions/x86_64-darwin-18/2.3.0/libxml-ruby-2.9.0/gem_make.out

An error occurred while installing libxml-ruby (2.9.0), and Bundler cannot continue.
Make sure that `gem install libxml-ruby -v '2.9.0'` succeeds before bundling.

In Gemfile:
  upnxt_community_lib_common was resolved to 1.7.49, which depends on
    upnxt_processing_lib_document was resolved to 2.0.0, which depends on
      libxml-

如果我想执行建议的命令“gem install libxml-ruby -v '2.9.0'”，我会得到同样的错误。
操作系统：MacOS莫哈韦，版本10.14。项目所需的Ruby版本：ruby 2.3.1p112（2016年4月26日修订版54768）[x86_64-达尔文18]
我也尝试了this，但没有任何帮助。
提前感谢您的帮助！