ActivtityPub Test: Add example for guppe actor
Adds a test for the guppe actor. We do indeed support their general format, but they don't use the correct mime type, see https://github.com/wmurphyrd/guppe/issues/32
Adds a test for the guppe actor. We do indeed support their general format, but they don't use the correct mime type, see https://github.com/wmurphyrd/guppe/issues/32