[Important] migrate actions elsewhere

Latest happenings teaches us that having a backup is fundamental

So a gitlab mirror has been created here:

https://gitlab.com/89luca89/distrobox.git

As explained on my twitter account, it has to do with suspicious activity on actions

Probably right now I'm overusing actions, so better to plan some moves to be more independent from github

- migrate website elsewhere
- migrate all github actions somewhere else

Suggestions are welcome to which services integrate well with github's PR and Commit process