forgejo-runner: try to configure dind

resources/chaosknoten/forgejo-runner/forgejo-runner/configuration.yaml.j2

@@ -23,6 +23,8 @@ runner:
     - alpine:docker://docker.io/library/alpine:latest
     # Debian
     - debian:docker://docker.io/library/debian:latest
+  envs:
+    DOCKER_HOST: tcp://dind_container.docker.internal:2375
 
 cache:
   enabled: false
@@ -40,7 +42,8 @@ container:
   ## Add /etc/gvisor-helper-resolv.conf to valid_volumes to make the bind-mount in options work.
   ## valid_volumes: ["/etc/gvisor-helper-resolv.conf:ro"]
   # Leave "-", so no docker host will be mounted in the job container.
-  docker_host: "-"
+  docker_host: "tcp://127.0.0.1:2376"
+  options: "--add-host=dind_container.docker.internal:host-gateway"
   force_pull: true
   force_rebuild: false