chore: Bump datadog-ci to 5.9.1 to pick up simple-git update#667

TalUsvyatsky merged 1 commit intomainDataDog/serverless-plugin-datadog:mainfrom

tal.usvyatsky/bump-simple-gitDataDog/serverless-plugin-datadog:tal.usvyatsky/bump-simple-gitCopy head branch name to clipboard