loongson/pypi: links for slack-client

loongson/mirror slack_client-0.3.0.tar.gz
loongson/mirror slack_client-0.3.0-py3-none-any.whl
loongson/mirror slack_client-0.2.2.tar.gz
loongson/mirror slack_client-0.2.2-py3-none-any.whl
loongson/mirror slack_client-0.2.1.tar.gz
loongson/mirror slack_client-0.2.1-py3-none-any.whl