remove reference to invalid file

windows/WinUI/WinUI.csproj

@@ -160,10 +160,6 @@
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>
-    <Page Include="Done.xaml">
-      <Generator>MSBuild:Compile</Generator>
-      <SubType>Designer</SubType>
-    </Page>
     <Page Include="JoinNetworkView.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>