Add check for older Qt versions

src/commands.cpp

@@ -1057,7 +1057,12 @@ void AOClient::cmdEvidence_Swap(int argc, QStringList argv)
         return;
     }
     if ((ev_id2 <= ev_size) && (ev_id1 <= ev_size)) {
+#if QT_VERSION < QT_VERSION_CHECK(5, 13, 0)
+        //swapItemsAt does not exist in Qt older than 5.13
+        area->evidence.swap(ev_id1, ev_id2);
+#else
         area->evidence.swapItemsAt(ev_id1, ev_id2);
+#endif
         sendEvidenceList(area);
         sendServerMessage("The evidence " + QString::number(ev_id1) + " and " + QString::number(ev_id2) + " have been swapped.");
     }