Merge branch 'frozen-string-enable-lib-gitlab-gitlab-import' into 'master'

Enable frozen string for GitLab import specs

See merge request gitlab-org/gitlab!20265

spec/lib/gitlab/gitlab_import/client_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::GitlabImport::Client do

spec/lib/gitlab/gitlab_import/importer_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::GitlabImport::Importer do

spec/lib/gitlab/gitlab_import/project_creator_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::GitlabImport::ProjectCreator do