Bump Verify.NUnit from 26.5.0 to 26.6.0 in /src

Bumps [Verify.NUnit](https://github.com/VerifyTests/Verify) from 26.5.0 to 26.6.0.
- [Release notes](https://github.com/VerifyTests/Verify/releases)
- [Commits](VerifyTests/Verify@26.5.0...26.6.0)

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

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

src/Directory.Packages.props

@@ -13,7 +13,7 @@
     <PackageVersion Include="System.Drawing.Common" Version="8.0.8" />
     <PackageVersion Include="Verify" Version="26.6.0" />
     <PackageVersion Include="Verify.DiffPlex" Version="3.1.0" />
-    <PackageVersion Include="Verify.NUnit" Version="26.5.0" />
+    <PackageVersion Include="Verify.NUnit" Version="26.6.0" />
     <PackageVersion Include="Verify.Phash" Version="3.1.0" />
   </ItemGroup>
 </Project>