fix some more warnings

Starting with .NET 8, setting  <UseMaui>true</UseMaui>  does not automatically include NuGet package references in your project.  Update your project by including this item:  <PackageReference Include="Microsoft.Maui.Controls" Version="8.0.61" />.  You can skip this warning by setting  <SkipValidateMauiImplicitPackageReferences>true</SkipValidateMauiImplicitPackageReferences>  in your project file.

Author: janusw

Source/OxyplotMauiSample/OxyplotMauiSample.csproj

@@ -58,6 +58,7 @@
 
 	<ItemGroup>
 		<PackageReference Include="OxyPlot.ExampleLibrary" Version="2.1.2" />
+		<PackageReference Include="Microsoft.Maui.Controls" Version="8.0.61" />
 	</ItemGroup>
 
 	<ItemGroup>