Bump Microsoft.VisualStudio.SlnGen from 11.2.3 to 11.2.6 (#1540)

Bumps [Microsoft.VisualStudio.SlnGen](https://github.com/microsoft/SlnGen) from 11.2.3 to 11.2.6.
- [Release notes](https://github.com/microsoft/SlnGen/releases)
- [Changelog](https://github.com/microsoft/slngen/blob/main/RELEASE.md)
- [Commits](microsoft/slngen@v11.2.3...v11.2.6)

---
updated-dependencies:
- dependency-name: Microsoft.VisualStudio.SlnGen
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Directory.Build.props

@@ -38,6 +38,6 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.VisualStudio.SlnGen" Version="11.2.3" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.VisualStudio.SlnGen" Version="11.2.6" PrivateAssets="all" />
   </ItemGroup>  
 </Project>