fix: dataToString correctness regression

It would incorrectly prepend garbage to the output and then truncate it, regression introduced in 6c150a04c0

src/persistence/serialize.cpp

@@ -42,7 +42,7 @@ QString dataToString(QByteArray data)
         return QString();
 
     // Remove the strlen
-    data.remove(0, i - 1);
+    data.remove(0, i);
     data.truncate(strlen);
 
     return QString(data);