Update landscape with KubeSlice sandbox project

[pnavali]

Adding CNCF sandbox project KubeSlice to landscape.

Pre-submission checklist:

Please check each of these after submitting your pull request:

• [x] Are you only including a repo_url if your project is 100% open source? If so, you need to pick the single best GitHub repository for your project, not a GitHub organization.
• [ ] Is your project closed source or, if it is open source, does your project have at least 300 GitHub stars?
• [x] Have you picked the single best (existing) category for your project?
• [x] Does it follow the other guidelines from the new entries section?
• [x] Have you added your SVG to hosted_logos and referenced it there?
• [x] Does your logo clearly state the name of the project/product and follow the other guidelines?
• [x] Does your project/product name match the text on the logo?
• [x] Have you verified that the Crunchbase data for your organization is correct (including headquarters and LinkedIn)?

[github-actions[bot]]

You can preview your changes by visiting this link.

[!NOTE] This feature is still experimental and may not work as expected in some cases. Please report any issues you find!

[pnavali]

For https://github.com/cncf/sandbox/issues/190

[castrojo]

Thanks and congrats!

[pnavali]

Thanks @castrojo