Update cookbook
- Bump to Ruby 2.6
- Switch from rubocop to cookstyle.
- Un-pin and update dependencies.
https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/9275
Signed-off-by: Ben Kochie bjk@gitlab.com
https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/9275
Signed-off-by: Ben Kochie bjk@gitlab.com