Community users are not allowed to do pull requests on CI files, so I'm making a PR request to bump ubuntu xenial to ubuntu bionic:
https://github.com/conan-io/conan-center-index/compare/master...ericLemanissier:bionic?expand=1

This follows:

• modern: bump base to Bionic conan-docker-tools#466

This blocks all PR to projects not suppoting Xenial (at least qt6)