build(deps): bump DiffEngine from 6.4.7 to 6.4.8 (#184)

Bumps [DiffEngine](https://github.com/VerifyTests/DiffEngine) from 6.4.7 to 6.4.8.
- [Release notes](https://github.com/VerifyTests/DiffEngine/releases)
- [Commits](https://github.com/VerifyTests/DiffEngine/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

src/ReactiveUI.Validation.Tests/ReactiveUI.Validation.Tests.csproj

@@ -23,7 +23,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="DiffEngine" Version="6.4.7" />    
+    <PackageReference Include="DiffEngine" Version="6.4.8" />    
   </ItemGroup>
 
   <ItemGroup>