racket: Update to 8.3
Bugfix and performance updates to Racket CS.
- Check that DrRacket can install packages
- Check that DrRacket can load and run an example .rkt file
- Check that the remacs editor project written in racket can be started from the command line
Reviewers: Triage Team, JoshStrobl
Reviewed By: Triage Team, JoshStrobl
Differential Revision: https://dev.getsol.us/D12305