Update readme with new ScubaGear graphic

[ahuynhMITRE]

🗣 Description

Add ScubaGear graphic to readme.

💭 Motivation and context

Motivation is to use the newly created ScubaGear graphic created by the comms team.
Closes #1486

🧪 Testing

N/A

✅ Pre-approval checklist

• This PR has an informative and human-readable title.
• PR targets the correct parent branch (e.g., main or release-name) for merge.
• Changes are limited to a single goal - eschew scope creep!
• Changes are sized such that they do not touch excessive number of files.
• Related issues these changes resolve are linked preferably via closing keywords.
• All relevant type-of-change labels added.
• All relevant project fields are set.
• All relevant repo and/or project documentation updated to reflect these changes.
• Unit tests added/updated to cover PowerShell and Rego changes.
• Functional tests added/updated to cover PowerShell and Rego changes.
• All relevant functional tests passed.
• All automated checks (e.g., linting, static analysis, unit/smoke tests) passed.

✅ Pre-merge checklist

• PR passed smoke test check.

• Feature branch has been rebased against changes from parent branch, as needed

  Use Rebase branch button below or use this reference to rebase from the command line.

• Resolved all merge conflicts on branch

• Notified merge coordinator that PR is ready for merge via comment mention

• Demonstrate changes to the team for questions and comments.
  (Note: Only required for issues of size Medium or larger)

✅ Post-merge checklist

• Feature branch deleted after merge to clean up repository.
• Verified that all checks pass on parent branch (e.g., main or release-name) after merge.

[mitchelbaker-cisa]

Can we remove the cisa.png from above the new graphic?

[ahuynhMITRE]

Can we remove the cisa.png from above the new graphic?

can do

[mitchelbaker-cisa]

Looks good thanks Andrew

[james-garriss]

Please remove old graphic from repo.