[Merge] ~renanrodrigo/update-notifier:respect-phasing into update-notifier:master

[Athos Ribeiro]

As for the SRU template:

I used `apt -o='Apt::Get::Always-Include-Phased-Updates=true' list --upgradable` instead of `apt show` in the [Test Plan]. That section of the template could be improved (e.g., list commands in the same order, add example outputs, etc).

Other than that, the [Test Plan] relies on a window where phased updates are available. I am interested on how the SRU team will look at that.
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https://code.launchpad.net/~renanrodrigo/update-notifier/+git/update-notifier/+merge/438009
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