chore: include response body if not valid JSON (#6796)
### Description
I noticed in our Ubuntu CI runs there's sometimes a `artifact
verification failed: Error making HTTP request: error decoding response
body: expected value at line 1 column 1`
[source](https://github.com/vercel/turbo/actions/runs/7210774346/job/19644690101#step:6:408)
It would be more useful if we could get an idea of what the response was
instead of a JSON parse error.
### Testing Instructions
Added unit tests
Closes TURBO-1934
