Bump DiffEngine from 11.4.1 to 12.0.0 (#703)

Bumps [DiffEngine](https://github.com/VerifyTests/DiffEngine) from 11.4.1 to 12.0.0.
- [Release notes](https://github.com/VerifyTests/DiffEngine/releases)
- [Commits](https://github.com/VerifyTests/DiffEngine/commits/12.0.0)

---
updated-dependencies:
- dependency-name: DiffEngine
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

src/ApprovalTests/ApprovalTests.csproj

@@ -11,7 +11,7 @@
     <Using Remove="System.Net.Http" />
     <PackageReference Include="Polyfill" Version="1.23.0" PrivateAssets="all" />
     <Compile Include="..\ApprovalUtilities\InternalsVisibleTo.cs" Link="InternalsVisibleTo.cs" />
-    <PackageReference Include="DiffEngine" Version="11.4.1" />
+    <PackageReference Include="DiffEngine" Version="12.0.0" />
     <PackageReference Include="EmptyFiles" Version="4.4.0" PrivateAssets="None" />
     <PackageReference Include="Fody" Version="6.8.0" PrivateAssets="all" />
     <PackageReference Include="Microsoft.Win32.Registry" Version="5.0.0" />