fix: Skip 'cat_bookmarks()' examples/tests if no 'pdftk'

* New `get_bookmarks_pdftools()` is not good enough
  for use with `set_bookmarks()` since doesn't know page numbers.
  Need to make sure `get_bookmarks_pdftk()` will be called
  in examples/tests otherwise skip.

.github/workflows/R-CMD-check.yaml

@@ -29,7 +29,7 @@ jobs:
       R_KEEP_PKG_SOURCE: yes
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - uses: r-lib/actions/setup-pandoc@v2
 

R/bookmarks.R

@@ -138,7 +138,10 @@ get_bookmarks_pdftools <- function(filename, use_names = TRUE) {
 #'         A "total_pages" attribute will be set for the theoretical total pages of
 #'         the concatenated document represented by the concatenated bookmarks.
 #' @examples
-#' if (supports_get_bookmarks() && supports_set_bookmarks() && require("grid", quietly = TRUE)) {
+#' if (supports_get_bookmarks() &&
+#'     supports_set_bookmarks() &&
+#'     supports_pdftk() &&
+#'     require("grid", quietly = TRUE)) {
 #'  # Create two different two-page pdf files
 #'  make_pdf <- function(f, title) {
 #'    pdf(f, onefile = TRUE, title = title)

tests/testthat/test-bookmarks.R

@@ -186,7 +186,7 @@ test_that("`get_count()` and `get_level()`", {
 })
 
 test_that("`cat_bookmarks()` works", {
-    skip_if_not(supports_get_bookmarks() && supports_set_bookmarks())
+    skip_if_not(supports_get_bookmarks() && supports_set_bookmarks() && supports_pdftk())
     bookmarks <- data.frame(title = c("Page 1", "Page 2"),
                             page = c(1L, 2L))
     f2 <- tempfile(fileext = ".pdf")