Assign category, not just tracker

[kvdb]

It seems a limitation of Redmine that I can't assign a person or group to issues that get
added in a certain tracker. However, when the issue is created with a certain category, issues can be assigned automatically to a person or group. That would make sure the tickets won't be added and there's no-one looking into them.

I'm using the https://github.com/getsentry/sentry-redmine fork.