message: Fix webc runner exports detection
  Related to webc upgrade
diff: @@ -111,7 +111,7 @@ impl Bindings for WitBindings {
  serde_cbor::from_slice(&serde_cbor::to_vec(value).unwrap())
  .map_err(|e| format!("could not parse WitBindings annotations: {e}"))?;
  - let mut wit_bindgen_filepath = value.wit.exports;
  + let mut wit_bindgen_filepath = value.exports().unwrap_or_default().to_string();
  for v in container.get_volumes() {
  let schema = format!("{v}://");
  