Use QStringList instead of QVariantList since the return value is a list of strings.

Co-Authored-By: diegopradogesto <d.pradogesto@ultimaker.com>

cura/PrinterOutputDevice.py

@@ -212,7 +212,7 @@ class PrinterOutputDevice(QObject, OutputDevice):
         self.uniqueConfigurationsChanged.emit()
 
     # Returns the unique configurations of the printers within this output device
-    @pyqtProperty("QVariantList", notify = uniqueConfigurationsChanged)
+    @pyqtProperty("QStringList", notify = uniqueConfigurationsChanged)
     def uniquePrinterTypes(self) -> List[str]:
         return list(set([configuration.printerType for configuration in self._unique_configurations]))
 
@@ -243,4 +243,4 @@ class PrinterOutputDevice(QObject, OutputDevice):
         if not self._firmware_updater:
             return
 
-        self._firmware_updater.updateFirmware(firmware_file)
+        self._firmware_updater.updateFirmware(firmware_file)