avoid CHEF-3694 in apt_preference resource

[grimm26]

Description

This avoids CHEF-3694 (Cloning resource attributes from prior resource) warnings when using apt_preferences.

Issues Resolved

https://github.com/chef-cookbooks/apt/issues/170

Check List

• [x] All tests pass. See https://github.com/chef-cookbooks/community_cookbook_documentation/blob/master/TESTING.MD
• [x] New functionality includes testing.
• [x] New functionality has been documented in the README if applicable
• [x] All commits have been signed for the Developer Certificate of Origin. See https://github.com/chef-cookbooks/community_cookbook_documentation/blob/master/CONTRIBUTING.MD

[tas50]

Thanks @grimm26