Merge branch 'fix-json-exceptions' of https://github.com/drybjed/debops into drybjed-fix-json-exceptions

The new Jinja2 3.x release changed the behaviour of 'to_json' filter
- it doesn't accept YAML lists as input anymore, only YAML dictionaries.
To fix this issue, we need to switch the filters to use YAML as
a transport between various places in the code, which permits lists to
be passed between variables.

There will be more places in the code that this might need to happen,
they will be dealt with on later commits.

Merge branch 'etckeeper-do-not-track-gitlab-runner' of https://github.com/julien-lecomte/debops into julien-lecomte-etckeeper-do-not-track-gitlab-runner

This patch changes all instances of 'with_flattened' lookup into
a 'loop' keyword, where 'q("flattened")' lookup is used to ensure that
the nested lists are properly restructured into flat YAML lists.
This fixes the schema issues reported by 'ansible-lint'.

Merge branch 'ser-influxdata-apt-repo' of https://github.com/ser/debops into ser-ser-influxdata-apt-repo

Now the URI points to particular distros.