Ensure to close the FinderSync extension socket on exit

$ python -m nxdrive bind-server Administrator $NXDRIVE_TEST_NUXEO_URL --password Administrator
...
sys:1: ResourceWarning: unclosed <socket.socket fd=7, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('0.0.0.0', 0)>