[Community Contributions] Free Spaced Repetition Scheduler

[L-M-Sherlock]

FSRS is a modern spaced repetition algorithm, which is used to predict the long-term memory of human students and schedule review tasks.

FSRS-rs has used a lot of useful features of burn, especially the Custom Training Loops.

Here is the repository: https://github.com/open-spaced-repetition/fsrs-rs