loongson/pypi: links for contextvars

loongson/pypi contextvars-2.4.tar.gz
loongson/pypi contextvars-2.4-py3-none-any.whl
loongson/mirror contextvars-2.3.tar.gz
loongson/mirror contextvars-2.2.tar.gz
loongson/mirror contextvars-2.1.tar.gz
loongson/mirror contextvars-2.0.tar.gz
loongson/mirror contextvars-1.0.tar.gz
loongson/mirror contextvars-1.0-py2.7.egg