Use 3.19 containers

[evgeni]

Why are you introducing these changes? (Problem description, related links)

We need a release that uses 3.19

What are the changes introduced in this pull request?

• Use 3.19

How to test this pull request

Steps to reproduce:

• CI

Checklist

• Tests added/updated (if applicable)
• Documentation updated (if applicable)

[evgeni]

@ehelms @ekohl so, following up from #424

• I created a 2.y-stable branch (or should it have been 2.1-stable? idk) based on 3f6912d (the later changes are not in 3.19)
• I've opened this PR targeting the 2.y-stable branch, updating nightly to 3.19
• Once this lands, we tag the result as 2.2.0 (or whatever) and create a 3.0-develop tag on master

[evgeni]

@ehelms how should we handle dev setup when branching? Ideally, it would follow, but right now it's not possible to configure compatible gems for plugins/hammer that match the foreman version.

[ehelms]

Let's worry about dev after, as you note, there's a few nuances to work out. This is an example workflow where I wonder if source containers would make that alignment easier.

[Odilhao]

Let's worry about dev after, as you note, there's a few nuances to work out. This is an example workflow where I wonder if source containers would make that alignment easier.

Should it use nightly directly for dev? Instead of using branched/stable for devs?