actions: shell: assert shell behavior (#788)

Refs https://code.forgejo.org/forgejo/runner/issues/150

Reviewed-on: https://code.forgejo.org/forgejo/end-to-end/pulls/788
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>

actions/example-shell/runner-config.yaml

@@ -0,0 +1,32 @@
+
+log:
+  level: debug
+
+runner:
+  file: .runner
+  capacity: 1
+  env_file: .env
+  timeout: 3h
+  insecure: false
+  fetch_timeout: 5s
+  fetch_interval: 2s
+  labels:
+      - docker:docker://code.forgejo.org/oci/node:22-bookworm
+      - alpine:docker://code.forgejo.org/oci/alpine:latest
+
+cache:
+  enabled: false
+  dir: ""
+  host: ""
+  port: 0
+
+container:
+  network: ""
+  privileged: false
+  options:
+  workdir_parent:
+  valid_volumes: []
+  docker_host: ""
+
+host:
+  workdir_parent: