survival no longer allows time point = Inf. This breaks sstable.survcomp

This line:
```
fit.surv <- summary(fit.surv0, time = Inf, extend = TRUE)
```
 is no longer valid due to a subset of times[is.finite(times)] in survival:::summary.survfit.

Shall we change it to:
```
fit.surv <- summary(fit.surv0, time = max(fit.surv0$times))
```