loongson/pypi: links for statsmodels

INFO: Because this project isn't in the mirror_whitelist, no releases from root/pypi are included.

loongson/pypi statsmodels-0.13.2.tar.gz
loongson/pypi statsmodels-0.13.2-cp39-cp39-linux_loongarch64.whl
loongson/pypi statsmodels-0.13.2-cp38-cp38-linux_loongarch64.whl
loongson/pypi statsmodels-0.13.2-cp37-cp37m-linux_loongarch64.whl
loongson/pypi statsmodels-0.13.2-cp36-cp36m-linux_loongarch64.whl