Bump chef-zero to 4.7.0 to retain Ruby 2.1 compatibility

https://github.com/chef/chef-zero/pull/219

The release builds were failing:

               [Builder: chef-zero] I | gem `install chef-zero --version '4.5.0' --bindir '/opt/gitlab/embedded/bin' --no-ri --no-rdoc': 39.2814s
               [Builder: chef-zero] I | Build chef-zero: 39.2832s
The following shell command exited with status 1:

    $ CFLAGS=-I/opt/gitlab/embedded/include -O2 CPPFLAGS=-I/opt/gitlab/embedded/include -O2 CXXFLAGS=-I/opt/gitlab/embedded/include -O2 LDFLAGS=-Wl,-rpath,/opt/gitlab/embedded/lib -L/opt/gitlab/embedded/lib LD_RUN_PATH=/opt/gitlab/embedded/lib PATH=/opt/gitlab/bin:/opt/gitlab/embedded/bin:/root/gems/ruby/2.1.0/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin PKG_CONFIG_PATH=/opt/gitlab/embedded/lib/pkgconfig /opt/gitlab/embedded/bin/gem install chef-zero --version '4.5.0' --bindir '/opt/gitlab/embedded/bin' --no-ri --no-rdoc

Output:

    (nothing)

Error:

    ERROR:  Error installing chef-zero:
	rack requires Ruby version >= 2.2.2.

Added 2 commits:

• 8495179c - Bump chef-zero to 4.7.0 to retain Ruby 2.1 compatibility
• 2f72482a - Update CHANGELOG for chef-zero bump

/cc: @rspeicher

This may need to be cherry-picked in other releases as well.

@stanhu thanks! I will just accept this MR, dev.gitlab.org is down atm so cannot really check what happened with the release.

Status changed to merged

mentioned in commit b9f9c006

mentioned in commit f589ad79

mentioned in commit 7a67f93e

mentioned in commit 51164768

mentioned in commit 5ca7959e

mentioned in commit 2a85e200

mentioned in commit 11853d25

mentioned in commit bf4f3c73

changed the description

added workflowstaging-ref label

added workflowproduction label and removed workflowstaging-ref label