testthat 3.1.1 and empty lines in snapshots

With testthat 3.1.1 empty lines are removed from snapshots.

E.g. if a function is

```r
bla <- function() {
  cli::cli_inform("thing")
  cli::cli_h2("bla")
  cli::cli_inform("another thing")
}
```

the snapshot will show no empty lines before and after the H2 whereas it used to.
