[Gemfile] Loosen test-kitchen constraint
[Gemfile] Loosen test-kitchen constraint

sh9189/logrotate,gleamicus/logrotate,Altiscale/logrotate,tfly-cookbooks/logrotate,tfly-cookbooks/logrotate,evertrue/logrotate,evertrue/logrotate,sh9189/logrotate,stevendanna/logrotate,stevendanna/logrotate,strebitz/logrotate,Altiscale/logrotate,strebitz/logrotate