The ubuntu-latest label moves to Ubuntu 26.04 and breaks workflows that pin nothing

On 17 September 2026 GitHub announced that the ubuntu-latest label is moving from Ubuntu 24.04 to 26.04, rolling out gradually between 19 October and 19 November 2026. The migration ships a JDK jump from 17 to 25, major-version bumps for Docker Compose and Helm, and the removal of a dozen preinstalled tools: workflows that don’t pin their runtime will break.