Fix build warning in pdf generator

warning: ‘void Poppler::Document::getPdfVersion(int*, int*) const’ is
deprecated [-Wdeprecated-declarations]

generators/poppler/generator_pdf.cpp

@@ -926,7 +926,13 @@ Okular::DocumentInfo PDFGenerator::generateDocumentInfo(const QSet<Okular::Docum
         }
         if (keys.contains(Okular::DocumentInfo::CustomKeys)) {
             int major, minor;
+#if POPPLER_VERSION_MACRO >= QT_VERSION_CHECK(21, 8, 0)
+            auto version = pdfdoc->getPdfVersion();
+            major = version.major;
+            minor = version.minor;
+#else
             pdfdoc->getPdfVersion(&major, &minor);
+#endif
             docInfo.set(QStringLiteral("format"), i18nc("PDF v. <version>", "PDF v. %1.%2", major, minor), i18n("Format"));
             docInfo.set(QStringLiteral("encryption"), pdfdoc->isEncrypted() ? i18n("Encrypted") : i18n("Unencrypted"), i18n("Security"));
             docInfo.set(QStringLiteral("optimization"), pdfdoc->isLinearized() ? i18n("Yes") : i18n("No"), i18n("Optimized"));
@@ -1615,7 +1621,7 @@ bool PDFGenerator::reparseConfig()
 void PDFGenerator::addPages(KConfigDialog *dlg)
 {
     PDFSettingsWidget *w = new PDFSettingsWidget(dlg);
-    ;
+
     dlg->addPage(w, PDFSettings::self(), i18n("PDF"), QStringLiteral("application-pdf"), i18n("PDF Backend Configuration"));
 }