feat: container support for OCI images with manifests missing platform field

[adrobuta]

Pull Request Submission Checklist

• Follows CONTRIBUTING guidelines
• Commit messages are release-note ready, emphasizing what was changed, not how
• Includes detailed description of changes
• Contains risk assessment (Low | Medium | High)
• Highlights breaking API changes (if applicable) - N/A
• Links to automated tests covering new functionality
• Includes manual testing instructions (if necessary) - Covered by automated test
• Updates relevant GitBook documentation (PR link: ___) - No doc updates needed
• Includes product update to be announced in the next stable release notes

What does this PR do?

Upgrades snyk-docker-plugin to v8.15.0, which adds support for scanning OCI images with manifests that don't include a platform field.

Changes:

• Bumps snyk-docker-plugin from local development link to 8.15.0
• Adds acceptance test: should correctly scan an OCI image with manifest missing platform field
• Updates package-lock.json

Where should the reviewer start?

1. Review the dependency change in package.json and package-lock.json.
2. Review the new acceptance test in test/jest/acceptance/snyk-container/container.spec.ts (lines 172-182)

What's the product update that needs to be communicated to CLI users?

The Snyk CLI now supports scanning OCI images with manifests that don't include platform fields, improving compatibility with various OCI registry implementations.

Risk assessment (Low | Medium | High)?

Low

• Dependency upgrade to a stable release version (v8.15.0)
• snyk-docker-plugin v8.15.0 has been tested in the plugin repository
• New acceptance test validates the functionality
• Only affects OCI image scanning where manifests lack platform fields

Any background context you want to provide?

Some OCI registries (especially custom/private registries) produce image manifests that don't include the platform field in their manifest structure. Without this fix, snyk container fails to scan these images.