Ensure that build folder gets generated before npm publish
Ensure that build folder gets generated before npm publish

So users using `npm install -g webtorrent-desktop` will always get a
working version.

webtorrent/webtorrent-desktop,feross/webtorrent-desktop,yciabaud/webtorrent-desktop,michaelgeorgeattard/webtorrent-desktop,feross/webtorrent-app,webtorrent/webtorrent-desktop,yciabaud/webtorrent-desktop,feross/webtorrent-desktop,feross/webtorrent-app,michaelgeorgeattard/webtorrent-desktop,feross/webtorrent-desktop,feross/webtorrent-app,michaelgeorgeattard/webtorrent-desktop,webtorrent/webtorrent-desktop,yciabaud/webtorrent-desktop