Matrix RSS feed per package

[merijn]

Right now I use an RSS feed from https://packdeps.haskellers.com/ to tell me when there's versions of my dependencies that are newer than my upperbound, but this doesn't help me detect when a new release of a (transitive) dependency breaks my build plan. Having an RSS feed that shows any time your package's build plan breaks would be great for monitoring package health.

Additionally I think this ties into #33. I think tying automated notifications/github issues into the matrix builder should probably be out of scope for the matrix builder, but once such an RSS feed it should be straightforward to develop a bot/GitHub webhook/pick your own hosting solution web integration that consumes such an RSS feed and opens an issue (whether this should be opt-in/opt-out is yet another discussion).