loongson/pypi: links for singleflight

loongson/mirror singleflight-0.1.3.tar.gz
loongson/mirror singleflight-0.1.2.tar.gz
loongson/mirror singleflight-0.1.1.tar.gz
loongson/mirror singleflight-0.1.0.tar.gz
loongson/mirror singleflight-0.1.0-py3.7.egg