Fix the test assembly ref

Author: anaisbetts

ReactiveUI.Tests/ReactiveUI.Tests_Android.csproj

@@ -79,7 +79,10 @@
     </Reference>
     <Reference Include="System.Runtime.Serialization" />
     <Reference Include="Xamarin.Android.Support.v4">
-      <HintPath>..\packages\Xamarin.Android.Support.v4.20.0.0.2\lib\MonoAndroid10\Xamarin.Android.Support.v4.dll</HintPath>
+      <HintPath>..\packages\Xamarin.Android.Support.v4.21.0.3.0\lib\MonoAndroid10\Xamarin.Android.Support.v4.dll</HintPath>
+    </Reference>
+    <Reference Include="Xamarin.Android.Support.v7.AppCompat">
+      <HintPath>..\packages\Xamarin.Android.Support.v7.AppCompat.21.0.3.0\lib\MonoAndroid403\Xamarin.Android.Support.v7.AppCompat.dll</HintPath>
     </Reference>
   </ItemGroup>
   <ItemGroup>