Prop 218: BugFix OnceUpon to v0.13.1

OnceUpon - Communal Story Telling With NFTs
BugFix in existing SmartContract

Current version: https://onceupon.community/
Future version: https://onceupon-delta.vercel.app/

Git: https://github.com/faboweb/onceupon/releases/tag/0.13.1

Changes:

- fix critical issue with game step function