Update prost requirement from 0.11.9 to 0.12.1 in /calendar-service#404

dependabot[bot] wants to merge 1 commit intomainsamgozman/validity.red:mainfrom

dependabot/cargo/calendar-service/main/prost-0.12.1samgozman/validity.red:dependabot/cargo/calendar-service/main/prost-0.12.1Copy head branch name to clipboard