Scrum I don't care about, but you need to keep a list of bugs somewhere. And a list of requests too, if you have multiple teams. What are you going to use for those?
Redmine works just fine.
I'm confused by your comment, jira doesn't force sprints or scrum on it's users. Could you explain?
Kia ora, if you dont need sprints then just use github projects.
Sprints solve a huge problem for my team: arbitrary, made up deadlines.
We run sprints, measure velocity and use that to plan work.