Update CountryData.Sample.MAUI.csproj

include package reference to address .net 8 useMaui=true automatic download deprecation

Author: frankodoom

sample/CountryData.Sample.MAUI/CountryData.Sample.MAUI/CountryData.Sample.MAUI.csproj

@@ -50,6 +50,7 @@
 	<ItemGroup>
 	  <PackageReference Include="ReactiveUI" Version="18.0.10" />
 	  <PackageReference Include="ReactiveUI.Fody" Version="18.0.10" />
+          <PackageReference Include="Microsoft.Maui.Controls" Version="8.0.21" />
 	</ItemGroup>
 
 	<ItemGroup>