fix: adjust button layout in PopupWindow for better spacing

Author: ayangabryl

QuotaBarWindows/Views/PopupWindow.xaml

@@ -110,9 +110,9 @@
                     <Button Grid.Column="0" Click="AddAccount_Click"
                             Style="{StaticResource SecondaryButtonStyle}"
                             HorizontalAlignment="Left">
-                        <StackPanel Orientation="Horizontal" Spacing="6">
+                        <StackPanel Orientation="Horizontal">
                             <TextBlock Text="+" Foreground="White" FontSize="16" FontWeight="Light"
-                                       VerticalAlignment="Center"/>
+                                       VerticalAlignment="Center" Margin="0,0,6,0"/>
                             <TextBlock Text="Add Account" Foreground="White" FontSize="13"
                                        VerticalAlignment="Center"/>
                         </StackPanel>