loongson/pypi: links for micropython-btreedb

loongson/mirror micropython-btreedb-0.3.2.tar.gz
loongson/mirror micropython-btreedb-0.3.1.tar.gz
loongson/mirror micropython-btreedb-0.3.tar.gz
loongson/mirror micropython-btreedb-0.2.tar.gz