Bump Verify.NUnit from 26.4.0 to 26.6.0

Bumps [Verify.NUnit](https://github.com/VerifyTests/Verify) from 26.4.0 to 26.6.0.
- [Release notes](https://github.com/VerifyTests/Verify/releases)
- [Commits](VerifyTests/Verify@26.4.0...26.6.0)

---
updated-dependencies:
- dependency-name: Verify.NUnit
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

test/Html2Markdown.Test/Html2Markdown.Test.csproj

@@ -9,7 +9,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
     <PackageReference Include="NUnit" Version="4.2.2" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
-    <PackageReference Include="Verify.NUnit" Version="26.4.0" />
+    <PackageReference Include="Verify.NUnit" Version="26.6.0" />
   </ItemGroup>
 
   <ItemGroup>