Fix duplicated header

Author: onesounds

Flow.Launcher/Resources/Pages/WelcomePage3.xaml

@@ -6,7 +6,6 @@
     xmlns:local="clr-namespace:Flow.Launcher.Resources.Pages"
     xmlns:ui="http://schemas.modernwpf.com/2019"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-    xmlns:ui="http://schemas.modernwpf.com/2019"
     Title="WelcomePage3"
     mc:Ignorable="d">
     <Page.Resources>

Flow.Launcher/Resources/Pages/WelcomePage4.xaml

@@ -6,7 +6,6 @@
     xmlns:local="clr-namespace:Flow.Launcher.Resources.Pages"
     xmlns:ui="http://schemas.modernwpf.com/2019"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-    xmlns:ui="http://schemas.modernwpf.com/2019"
     Title="WelcomePage4"
     d:DesignHeight="450"
     d:DesignWidth="800"

Flow.Launcher/Resources/Pages/WelcomePage5.xaml

@@ -4,7 +4,6 @@
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:local="clr-namespace:Flow.Launcher.Resources.Pages"
-    xmlns:ui="http://schemas.modernwpf.com/2019"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:ui="http://schemas.modernwpf.com/2019"
     xmlns:userSettings="clr-namespace:Flow.Launcher.Infrastructure.UserSettings;assembly=Flow.Launcher.Infrastructure"