BogdanVanca's solution worked for me as well. For the Pynq-Z1 board, I added the line:
<board name="Xilinx_PYNQ-Z1" display_name="Xilinx PYNQ-Z1" family="zynq" part="xc7z020clg400-1" device="xc7z020" package="clg400" speedgrade="-1" vendor="pynq.io" />