Bump DiffEngine from 6.3.0 to 6.3.1 (#713)

Bumps [DiffEngine](https://github.com/VerifyTests/DiffEngine) from 6.3.0 to 6.3.1.
- [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/Shouldly/Shouldly.csproj

@@ -21,7 +21,7 @@
     <PublishRepositoryUrl>true</PublishRepositoryUrl>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="DiffEngine" Version="6.3.0" />
+    <PackageReference Include="DiffEngine" Version="6.3.1" />
     <Content Include="build.targets" PackagePath="build\Shouldly.targets" />
     <Content Include="buildMultiTargeting.targets" PackagePath="buildMultiTargeting\Shouldly.targets" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" Condition="$(Configuration) == 'Release'" />