message: fix: update field type
diff: @@ -36,7 +36,7 @@ class PythonFilesystem : public FileSystem {
  private:
  const string prefix;
  const string name;
  - const py::object filesystem;
  + const AbstractFileSystem filesystem;
  string stripPrefix(string input) {
  if (CanHandleFile(input)) {
  return input.substr(prefix.size());
  @@ -46,7 +46,7 @@ private:
  }
  public:
  - explicit PythonFilesystem(const string name, const py::object filesystem)
  + explicit PythonFilesystem(const string name, const AbstractFileSystem filesystem)
  : prefix(name + "://"), name(name), filesystem(filesystem) {
  }
  