Qt: Swap point size for pixel size in a few places

Make sizes consistent between Windows and MacOS.

src/duckstation-qt/gamelistwidget.cpp

@@ -324,7 +324,7 @@ void GameListModel::createPlaceholderImage(QImage& image, const QImage& placehol
   if (painter.begin(&image))
   {
     QFont font;
-    font.setPointSize(std::max(static_cast<int>(32.0f * scale), 1));
+    font.setPixelSize(std::max(static_cast<int>(64.0f * scale), 1));
     painter.setFont(font);
     painter.setPen(Qt::white);
 
@@ -2026,7 +2026,7 @@ void GameListGridView::resizeEvent(QResizeEvent* e)
 void GameListGridView::onCoverScaleChanged(float scale)
 {
   QFont font;
-  font.setPointSizeF(20.0f * scale);
+  font.setPixelSize(std::max(static_cast<int>(30.0f * scale), 1));
   setFont(font);
 
   updateLayout();

src/duckstation-qt/gamepatchsettingswidget.cpp

@@ -23,7 +23,7 @@ GamePatchDetailsWidget::GamePatchDetailsWidget(std::string name, const std::stri
   m_ui.setupUi(this);
 
   QFont title_font(m_ui.name->font());
-  title_font.setPointSizeF(title_font.pointSizeF() + 4.0f);
+  title_font.setPixelSize(17);
   title_font.setBold(true);
   m_ui.name->setFont(title_font);
   m_ui.name->setText(QString::fromStdString(m_name));
@@ -120,7 +120,7 @@ void GamePatchSettingsWidget::reloadList()
   {
     QLabel* label = new QLabel(tr("No patches are available for this game."), container);
     QFont font(label->font());
-    font.setPointSizeF(font.pointSizeF() + 2.0f);
+    font.setPixelSize(15);
     font.setBold(true);
     label->setFont(font);
     layout->addWidget(label);

src/duckstation-qt/postprocessingsettingswidget.cpp

@@ -353,7 +353,8 @@ void PostProcessingShaderConfigWidget::createUi()
       {
         QLabel* label = new QLabel(QString::fromStdString(option.category), this);
         QFont label_font(label->font());
-        label_font.setPointSizeF(12.0f);
+        label_font.setPixelSize(16);
+        label_font.setBold(true);
         label->setFont(label_font);
         m_layout->addWidget(label, row++, 0, 1, 3, Qt::AlignLeft);
       }