chore(deps): update dependency reactiveui.testing to 20.1.63

Author: renovate[bot]

src/ReactiveMvvm.Tests/ReactiveMvvm.Tests.csproj

@@ -13,7 +13,7 @@
     <PackageReference Include="FluentAssertions" Version="6.12.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
     <PackageReference Include="NSubstitute" Version="5.1.0" />
-    <PackageReference Include="ReactiveUI.Testing" Version="20.1.1" />
+    <PackageReference Include="ReactiveUI.Testing" Version="20.1.63" />
     <PackageReference Include="xunit" Version="2.9.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
       <PrivateAssets>all</PrivateAssets>