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] <[email protected]>

src/Directory.Packages.props

@@ -16,6 +16,6 @@
     <PackageVersion Include="ProjectDefaults" Version="1.0.135" />
     <PackageVersion Include="System.ComponentModel.Annotations" Version="5.0.0" />
     <PackageVersion Include="Verify.NServiceBus" Version="10.3.0" />
-    <PackageVersion Include="Verify.Nunit" Version="26.5.0" />
+    <PackageVersion Include="Verify.Nunit" Version="26.6.0" />
   </ItemGroup>
 </Project>