Bump knife-ec2 to 0.19.12
Bump knife-ec2 to 0.19.12

This pull request was triggered automatically via Expeditor when knife-ec2 0.19.12 was promoted to Rubygems.

This change falls under the obvious fix policy so no Developer Certificate of Origin (DCO) sign-off is required.

chef/chef-dk,chef/chef-dk,chef/chef-dk