Use fluent theme for BindingDemo

samples/BindingDemo/App.xaml

@@ -3,7 +3,7 @@
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     x:Class="BindingDemo.App">
     <Application.Styles>
-        <StyleInclude Source="avares://Avalonia.Themes.Default/DefaultTheme.xaml"/>
+        <FluentTheme />
         <StyleInclude Source="avares://Avalonia.Themes.Default/Accents/BaseLight.xaml"/>
     </Application.Styles>
-</Application>
+</Application>

samples/BindingDemo/BindingDemo.csproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\src\Avalonia.Diagnostics\Avalonia.Diagnostics.csproj" />
-    <ProjectReference Include="..\..\src\Avalonia.Themes.Default\Avalonia.Themes.Default.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.Themes.Fluent\Avalonia.Themes.Fluent.csproj" />
     <ProjectReference Include="..\..\src\Linux\Avalonia.LinuxFramebuffer\Avalonia.LinuxFramebuffer.csproj" />
     <ProjectReference Include="..\MiniMvvm\MiniMvvm.csproj" />
   </ItemGroup>