loongson/pypi: links for sympound

loongson/mirror sympound-0.6.0.tar.gz
loongson/mirror sympound-0.5.0.tar.gz
loongson/mirror sympound-0.4.0.tar.gz
loongson/mirror sympound-0.3.0.tar.gz
loongson/mirror sympound-0.2.0.tar.gz