Only set TrimBox in postprocessing

Removes setting CropBox in PDF postprocessing, fixes https://gitlab.pagedmedia.org/tools/pagedjs-cli/issues/9

This box is already covered by TrimBox and is not recommend to use https://www.prepressure.com/pdf/basics/page-boxes

src/postprocesser.js

@@ -192,9 +192,7 @@ class PostProcesser extends EventEmitter {
           pdfPage.index,
         );
 
-      // pdfPage.set("ArtBox", rectangle);
-      pdfPage.set("TrimBox", rectangle);
-      pdfPage.set("CropBox", rectangle);
+        pdfPage.set("TrimBox", rectangle);
     });
 
   }