loongson/pypi: links for dpkg-json

loongson/mirror dpkg_json-0.1.21.tar.gz
loongson/mirror dpkg_json-0.1.21-cp38-cp38-manylinux_2_24_x86_64.whl
loongson/mirror dpkg_json-0.1.21-cp37-cp37m-manylinux_2_24_x86_64.whl
loongson/mirror dpkg_json-0.1.21-cp36-cp36m-manylinux_2_24_x86_64.whl
loongson/mirror dpkg_json-0.1.20.tar.gz
loongson/mirror dpkg_json-0.1.20-cp36-cp36m-manylinux_2_24_x86_64.whl