This workflow will download the current snaps published in the `candidate`
channel for all architectures and check them for packages with published
Ubuntu Security Notices. If it finds one, it will trigger a build of the
snap recipe:
https://code.launchpad.net/~subsurface/+snap/subsurface-stable
This will rebuild the snap with patched packages and publish it to the
`candidate` channel.
Signed-off-by: Michał Sawicz <michal@sawicz.net>