Update analyzer test dependency

Author: AArnott

src/tests/Microsoft.VisualStudio.Composition.Analyzers.Tests/Microsoft.VisualStudio.Composition.Analyzers.Tests.csproj

@@ -7,8 +7,8 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.CodeFix.Testing.XUnit" Version="1.0.1-beta1.20059.2" />
-    <PackageReference Include="Microsoft.CodeAnalysis.VisualBasic.CodeFix.Testing.XUnit" Version="1.0.1-beta1.20059.2" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.CodeFix.Testing.XUnit" Version="1.0.1-beta1.20478.1" />
+    <PackageReference Include="Microsoft.CodeAnalysis.VisualBasic.CodeFix.Testing.XUnit" Version="1.0.1-beta1.20478.1" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" version="2.10.0" />
     <PackageReference Include="Microsoft.CodeAnalysis.VisualBasic.Workspaces" version="2.10.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.1" />