update castv2 dependency to fix `npm audit` warning
update castv2 dependency to fix `npm audit` warning

For: https://github.com/webtorrent/webtorrent-desktop/issues/1599

feross/webtorrent-app,webtorrent/webtorrent-desktop,webtorrent/webtorrent-desktop,feross/webtorrent-app,webtorrent/webtorrent-desktop,feross/webtorrent-app