Return hyphenated run IDs

In earlier MLflow versions, it was required that run IDs always be UUIDs with the hyphens removed. However, in later versions this requirement was removed. In `mlflow-faculty`, we accept either format (`uuid.UUID()` accepts either as input), but still return non-hyphenated UUIDs to MLflow.

For consistency with how UUIDs are exposed everywhere else in the platform (including in the Faculty Python library's experiment client itself), it would be good to update `mlflow-faculty` to return hyphenated run IDs.