Remove Rails version ceiling in the sfu_api gem
Remove Rails version ceiling in the sfu_api gem

This allows the gem to continue work with newer versions of Rails. We
will still have to monitor and fix any potential breaking changes.

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms