Use correct font in painter in **Memory Viewer** dialog.

Although the font was set up in the **Memory Viewer** dialog's main
widget, the viewport's painter that actually renders the text was still
using the default font.

When a theme (other than **System**) was used, this resulted in the grid
and the text having a mismatched size, which was specially noticeable
when the font size was made large or small:

| Before | After |
| --- | --- |
| ![DME - Memory Viewer (incorrect font size) png](https://github.com/aldelaro5/dolphin-memory-engine/assets/1853278/08e2597e-aa6a-4c6e-be5c-1fa46555b340) | ![DME - Memory Viewer (correct font size)](https://github.com/aldelaro5/dolphin-memory-engine/assets/1853278/348ee9f0-c407-4666-b040-caac62a63fb1) |

Source/GUI/MemViewer/MemViewer.cpp

@@ -1007,6 +1007,7 @@ void MemViewer::paintEvent(QPaintEvent* event)
   (void)event;
 
   QPainter painter(viewport());
+  painter.setFont(font());
   painter.setPen(QColor(Qt::black));
 
   renderSeparatorLines(painter);