configure `license_finder`
update working Ruby version
update `rubocop` configuration
update `chefspec` to use `SoloRunner`
update deprecated `serverspec` configuration
add `sensitive` attribute to resources:

* mask potentially sensitive output for some templates and command execution
* bump minimum Chef requirement to >= 11.13
configure `test-kitchen` driver via environment
add `bundle-audit` to CI run
fix incorrect spec matchers
support extension installation via `databases` key