loongson/pypi: links for slack-backup-python

loongson/mirror slack-backup-python-1.4.tar.gz
loongson/mirror slack_backup_python-1.4-py2-none-any.whl
loongson/mirror slack-backup-python-1.3.tar.gz
loongson/mirror slack_backup_python-1.3-py2-none-any.whl