[CardInfo] use QString QHash instead of QVariantHash for properties (#7063)

* [CardInfo] use QString QHash instead of QVariantHash for properties

* bump CACHE_VERSION

* cleanups

libcockatrice_card/libcockatrice/card/database/card_database_cache.cpp

@@ -13,12 +13,11 @@
 #include <QElapsedTimer>
 #include <QFile>
 #include <QSaveFile>
-#include <QVariantHash>
 
 namespace
 {
 constexpr quint32 CACHE_MAGIC = 0x43445243; // "CDRC"
-constexpr quint32 CACHE_VERSION = 1;
+constexpr quint32 CACHE_VERSION = 2;
 
 // ---- Primitives -----------------------------------------------------------
 
@@ -34,11 +33,11 @@ QString readString(QDataStream &in)
     return s;
 }
 
-// Stores a QVariantHash as a single pre-serialized blob. The reader keeps the
-// blob as-is and materializes the QVariantHash lazily on first query, which is
+// Stores a QHash<QString, QString> as a single pre-serialized blob. The reader keeps the
+// blob as-is and materializes the QHash<QString, QString> lazily on first query, which is
 // what removes the allocation storm from database load (see card_info.cpp /
 // printing_info.cpp).
-void writeHashBlob(QDataStream &out, const QVariantHash &h)
+void writeHashBlob(QDataStream &out, const QHash<QString, QString> &h)
 {
     QByteArray blob;
     QDataStream blobOut(&blob, QIODevice::WriteOnly);