Update to RFC 9260

[philipch07]

Currently, the SCTP implementation is based off of RFC 4960 which is obseleted by RFC 9260. It would be nice to update SCTP to RFC 9260!

This issue can help to keep track of the different things that were necessary to update to RFC 9260. I'm not super sure about creating sub-issues for everything, but if anyone wants to help out, it would probably be a good way to manage tasks!

[philipch07]

One PR has already started on this: #299

I took a look and was able to update the rest of the rtx_timer impl to conform to RFC 9260: #403