loongson/pypi: links for mmcif-sitegen

loongson/mirror mmcif_sitegen-0.27.1.tar.gz
loongson/mirror mmcif_sitegen-0.27.tar.gz
loongson/mirror mmcif.sitegen-0.26.tar.gz
loongson/mirror mmcif.sitegen-0.25.tar.gz
loongson/mirror mmcif.sitegen-0.24.tar.gz
loongson/mirror mmcif.sitegen-0.23.tar.gz
loongson/mirror mmcif.sitegen-0.22.tar.gz
loongson/mirror mmcif.sitegen-0.21.tar.gz
loongson/mirror mmcif.sitegen-0.20.tar.gz
loongson/mirror mmcif.sitegen-0.10.tar.gz