Remove package cloud from our supporters.

They're changing the requirements for open source projects and we never fully
realized what using them could mean. Since I don't have the resources to
handle either of those problems we're just going to let them close our open
source plan.

Testing Done:
Ran `npm run hugo:server` locally verified everything looked fine and greped for other references to packagecloud of which I found none.

Reviewed at https://reviews.imfreedom.org/r/783/