runner: valid_volumes regex matches the full source:target form

runner/config.yaml

@@ -25,12 +25,11 @@ container:
   options: "-v cargoxx-cache-store:/srv/cargoxx-cache/store
             -v cargoxx-cache-keys:/srv/cargoxx-cache/keys:ro"
   workdir_parent: /workspace
-  # Whitelist regex of bind sources act_runner is allowed to forward to
-  # spawned job containers. Must include the cache + key volumes named
-  # in `options` above (otherwise act_runner silently strips them).
+  # Whitelist regex of bind specs act_runner forwards to spawned job
+  # containers. The regex matches the full `source:target[:opts]`
+  # string, so a permissive prefix is enough.
   valid_volumes:
-    - "^cargoxx-cache-store$"
-    - "^cargoxx-cache-keys$"
+    - "^cargoxx-cache-(store|keys):"
   docker_host: "unix:///var/run/docker.sock"
   force_pull: false