Automatically fetch updated easystats citations instead of hardcoding in `cite_easystats()`

[rempsyc]

Automatically fetch updated easystats citations instead of hardcoding in cite_easystats() so we don't have to constantly manually update all those changing citations.

[rempsyc]

Also should cite_easystats() move to the easystats meta-package? I think it would make more sense than in report??