feat!: use default renovate install mode with slim image
- The default template is now fully self-contained
- The default template uses the slim image
- the dind template now forwards to the default template
- All images are now pulled from ghcr.io
- fixes #23 (closed)
BREAKING CHANGE: The default image is now the slim image. The docker images are now pulled from ghcr.io. DinD is no longer supported.