Github Workflows: Run ansible-lint without an action.

We used a Github Action to run anisble-lint, but it has not have a
release since 2019, and has not been updated in a year. This action is
showing some issues when evaluating current playbooks.

This PR substitute the action previously used with a shell script
directly define in the workflow job. The ansible-core version was
pinned to the currently available on Fedora 25, 2.11.6.