Slack: GitHub Deployment notifications filter

[derwasp]

Currently it's possible to create filtered subscription for a bunch of events, but it's not possible for the deployment events.
Since we are deploying quite often, we have way too many notifications and in reality are only looking at the failed ones.

It would be extremely cool if we could filter based on the deployment state, like so:
/github subscribe myawesomeorg/MyIncredibleProject deployments +status:failure

Related to #913

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[simonbrandhof]

Filtering by environment is another use-case for this improvement.

[stale[bot]]

Is this still relevant? If so, just comment with any updates and we'll leave it open. Otherwise, if there is no further activity, it will be closed.

[arielkirkwood]

I think it’s still relevant.