make missing eval_time error in augment more informative

[EmilHvitfeldt]

To close #1049

Updated tests tidymodels/extratests#177

library(censored)

proportional_hazards() %>%
  fit(Surv(time, status) ~ ., data = lung) %>% 
  augment(new_data = lung)
#> Error in `augment()`:
#> ✖ The `eval_time` argument is missing, with no default.
#> ℹ `eval_time` is required to be able to calculate predictions of survival
#>   probability.

[hfrick]

Nice! 👾

[github-actions]

This pull request has been automatically locked. If you believe you have found a related problem, please file a new issue (with a reprex: https://reprex.tidyverse.org) and link to this issue.