Bump github.com/docker/cli from 20.10.8+incompatible to 20.10.15+incompatible#15

dependabot[bot] wants to merge 1 commit intomainterencet-dev/notation:mainfrom

dependabot/go_modules/github.com/docker/cli-20.10.15incompatibleterencet-dev/notation:dependabot/go_modules/github.com/docker/cli-20.10.15incompatibleCopy head branch name to clipboard