build(deps): bump DiffEngine from 6.5.6 to 6.5.7 in /src (#354)

Bumps [DiffEngine](https://github.com/VerifyTests/DiffEngine) from 6.5.6 to 6.5.7.
- [Release notes](https://github.com/VerifyTests/DiffEngine/releases)
- [Commits](https://github.com/VerifyTests/DiffEngine/commits)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/Directory.build.props

@@ -27,7 +27,7 @@
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" />
     <PackageReference Include="Xunit.StaFact" Version="1.0.37" />
-    <PackageReference Include="DiffEngine" Version="6.5.6" />
+    <PackageReference Include="DiffEngine" Version="6.5.7" />
     <PackageReference Include="FluentAssertions" Version="5.10.3" />
     <PackageReference Include="ReactiveUI.Testing" Version="13.*" />
     <PackageReference Include="PublicApiGenerator" Version="10.2.0" />