fix: symbols link error on mingw64

Author: saturneric

src/ui/model/GpgKeyTableProxyModel.cpp

@@ -34,7 +34,7 @@
 #include "core/struct/cache_object/AllFavoriteKeyPairsCO.h"
 #include "core/utils/GpgUtils.h"
 
-namespace GpgFrontend {
+namespace GpgFrontend::UI {
 
 GpgKeyTableProxyModel::GpgKeyTableProxyModel(
     QSharedPointer<GpgKeyTableModel> model, GpgKeyTableDisplayMode display_mode,
@@ -274,4 +274,4 @@ auto GpgKeyTableProxyModel::headerData(int section, Qt::Orientation orientation,
 
   return sourceModel()->headerData(section, orientation, role);
 }
-}  // namespace GpgFrontend
+}  // namespace GpgFrontend::UI

src/ui/model/GpgKeyTableProxyModel.h

@@ -33,10 +33,9 @@
 
 #include "core/model/GpgKeyTableModel.h"
 
-namespace GpgFrontend {
+namespace GpgFrontend::UI {
 
-class GPGFRONTEND_CORE_EXPORT GpgKeyTableProxyModel
-    : public QSortFilterProxyModel {
+class GpgKeyTableProxyModel : public QSortFilterProxyModel {
   Q_OBJECT
  public:
   using KeyFilter = std::function<bool(const GpgKey &)>;
@@ -109,4 +108,4 @@ class GPGFRONTEND_CORE_EXPORT GpgKeyTableProxyModel
   QFontMetrics default_metrics_;
 };
 
-}  // namespace GpgFrontend
+}  // namespace GpgFrontend::UI