wxGUI/gui_core: fix preferences dialog rendered height on wxPython 4.1.1 (#1825)

In cases where a scrolled panel is used.

gui/wxpython/gui_core/preferences.py

@@ -130,7 +130,6 @@ class PreferencesBaseDialog(wx.Dialog):
                       flag=wx.EXPAND | wx.ALL, border=5)
 
         self.SetSizer(mainSizer)
-        mainSizer.Fit(self)
 
     def OnDefault(self, event):
         """Button 'Set to default' pressed"""