fix: Skip certain tests if ghostscript version > 9.55

* ghostscript v10.3 breaks code to disable old bookmarks
* Now skip tests that verify old bookmarks disabled if detects
  ghostscript version is strictly greater than 9.55

see #59

DESCRIPTION

@@ -2,7 +2,7 @@ Encoding: UTF-8
 Package: xmpdf
 Type: Package
 Title: Edit 'XMP' Metadata and 'PDF' Bookmarks and Documentation Info
-Version: 0.2.0-0
+Version: 0.2.0-1
 Description: Edit 'XMP' metadata <https://en.wikipedia.org/wiki/Extensible_Metadata_Platform> 
     in a variety of media file formats as well as 
     edit bookmarks (aka outline aka table of contents) and documentation info entries in 'pdf' files.

R/bookmarks.R

@@ -436,7 +436,7 @@ set_bookmarks_gs <- function(bookmarks, input, output = input) {
               shQuote(input),
               shQuote(system.file("gs/pdfmark_restore.txt", package = "xmpdf")),
               shQuote(metafile))
-    xmpdf_system2(cmd, args)
+    stdout <- xmpdf_system2(cmd, args)
     if (input == output) {
         file.copy(target, output, overwrite = TRUE)
     }

tests/testthat/test-bookmarks.R

@@ -72,6 +72,9 @@ test_that("set_bookmarks_gs", {
     expect_equal(nrow(bm), 3L)
     expect_equal(attr(bm, "total_pages"), 2L)
 
+    gs_version <- numeric_version(system2(find_gs_cmd(), "--version", stdout = TRUE))
+    skip_if_not(gs_version <= "9.55.0")
+
     # Does Unicode work
     skip_if_not(l10n_info()[["UTF-8"]])
     skip_on_os("mac") # CRAN checks on macOS 14
@@ -174,6 +177,10 @@ test_that("bookmarks_pdftools", {
     # Does Unicode work
     skip_if_not(l10n_info()[["UTF-8"]])
     skip_on_os("mac") # CRAN checks on macOS 14
+    if(supports_gs()) {
+        gs_version <- numeric_version(system2(find_gs_cmd(), "--version", stdout = TRUE))
+        skip_if_not(gs_version <= "9.55.0")
+    }
     bookmarks <- data.frame(title = c("R\u5f88\u68d2\uff01", "Page 1", "Page 2"),
                             level = c(1, 2, 2),
                             page = c(1L, 1L, 2L))