Update test Issue874: Also more text on page 2

Page two has had four more characters added, which is now delected by this xref-stream fix

src/UglyToad.PdfPig.Tests/Integration/GithubIssuesTests.cs

@@ -478,7 +478,7 @@
                 Assert.Equal(1939, page1.Letters.Count);
 
                 var page2 = document.GetPage(2);
-                Assert.Equal(2430, page2.Letters.Count);
+                Assert.Equal(2434, page2.Letters.Count);
             }
 
             using (var document = PdfDocument.Open(doc, new ParsingOptions() { UseLenientParsing = true, SkipMissingFonts = false }))