Clean devtools test

[EmilHvitfeldt]

to close #273

This removes all messages and warnings i was able to remove when running the tests.

There is still this one which i think is related to tidymodels/butcher#286

Registered S3 method overwritten by 'butcher':
  method                 from    
  as.character.dev_topic generics

and this one is fixed in {poissonreg} dev

posterior_linpred(..., transform=TRUE) please call posterior_epred(), which provides equivalent functionality.