loongson/pypi: links for pushtogether-math

loongson/mirror pushtogether-math-0.1.50.tar.gz
loongson/mirror pushtogether-math-0.1.40.tar.gz
loongson/mirror pushtogether-math-0.1.20.tar.gz
loongson/mirror pushtogether_math-0.1.20-py3.6.egg