new playbook for obsolete packages.

15 minutes, so it's probably not necessary to trigger it by hand to speed things

up.

## Blocked upgrades

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Outdated packages are packages that don't currently relate to one of the

configured package archives. Some causes for the presence of outdated packages

might be:

* leftovers from an OS upgrade

* apt source got removed but not packages installed from it

* patched package was installed locally

If you want to know which packages are marked as obsolete, you can use the

following two commands:

    apt list "?obsolete"

    # The following will mainly print the same list as above, but there might be

    # some more in its list.

    DEBUG=1 /usr/share/prometheus-node-exporter-collectors/apt_info.py

Check the state of each package with `apt policy $package` to determine what

needs to be done with it. If most cases, the packages can just be purged, but

maybe not if they are obsolete because an apt source was lost. In that latter

case, you may want to check out why the source was removed and make sure to

bring it back.

## Out of date package lists

The `AptUpdateLagging` looks like this: