loongson/pypi: links for arithmetic

loongson/mirror arithmetic-0.6.2.tar.gz
loongson/mirror arithmetic-0.6.1.tar.gz
loongson/mirror arithmetic-0.5.tar.gz
loongson/mirror arithmetic-0.4.tar.gz
loongson/mirror arithmetic-0.3.tar.gz
loongson/mirror arithmetic-0.2.tar.gz
loongson/mirror arithmetic-0.1.tar.gz