CatLight 3 preview 5 - GitLab Merge Requests and improved notifications

The new version of CatLight can monitor merge requests in GitLab. The app will show desktop notifications for incoming MRs, and display a list of incoming and outgoing MRs on the dashboard.

We also improved toast notifications. We fixed a long-standing issue on Windows OS, and now the app dashboard will be opened when you click on the notification. New notifications will also have a "web" button that will take you directly to the alerted build, release or pull request.