fix: update auto and add slack plugin

[benoitdeziel]

Description

This PR adds the Slack plugin for Auto to post release note to a channel.

For now this will post to a temporary channel. This will be changed to #chapter-frontend in a future PR.

Checklist

• [ ] Test any new configuration on a repo using npm link

[benoitdeziel]

:rocket: PR was released in eslint-config-landr@0.7.0, stylelint-config-landr@0.2.0 :rocket: