go.mod: bump golang.org/x/sync from 0.19.0 to 0.20.0#85

dependabot[bot] wants to merge 1 commit intomainlovromazgon/impromptu:mainfrom

dependabot/go_modules/golang.org/x/sync-0.20.0lovromazgon/impromptu:dependabot/go_modules/golang.org/x/sync-0.20.0Copy head branch name to clipboard