Double check that predict(...) raises for http errors

[machow]

Describe the bug

From meeting with RStudio SE team, it looks like predict tried to json decode an error page.

To Reproduce

Create an endpoint on RStudio Connect and set it so one of us can't access. Then run something like...

from vetiver.server import predict
from vetiver.data import mtcars

endpoint = "URL_TO_ENDPOINT"
predict(endpoint, mtcars)

We may need to include response.raise_for_status() in predict