structuredAttrs is enabled

trying https://github.com/rust-lang/mdBook/archive/refs/tags/v0.5.3.tar.gz
  % Total    % Received % Xferd  Average Speed  Time    Time    Time   Current
                                 Dload  Upload  Total   Spent   Left   Speed
  0      0   0      0   0      0      0      0                              0
100 957.9k   0 957.9k   0      0  1.71M      0                              0
unpacking source archive /build/download.tar.gz