ci: fix post-release workflow permissions

[akijakya]

Description

As per the documentation, contents: write permission is needed for creating references.

Type of Change

[X] Bug Fix
[ ] New Feature
[ ] Breaking Change
[ ] Refactor
[ ] Documentation
[ ] Other (please describe)

Checklist

• [X] I have read the contributing guidelines
• [ ] Existing issues have been referenced (where applicable)
• [X] I have verified this change is not present in other open pull requests
• [ ] Functionality is documented
• [X] All code style checks pass
• [ ] New code contribution is covered by automated tests
• [X] All new and existing tests pass

[github-actions[bot]]

Hey!

Your images are ready:

• ghcr.io/openclarity/vmclarity-apiserver-dev:pr1767-6ab0e3ac574606c46830ac02049d6facd60a0935
• ghcr.io/openclarity/vmclarity-cli-dev:pr1767-6ab0e3ac574606c46830ac02049d6facd60a0935
• ghcr.io/openclarity/vmclarity-cr-discovery-server-dev:pr1767-6ab0e3ac574606c46830ac02049d6facd60a0935
• ghcr.io/openclarity/vmclarity-orchestrator-dev:pr1767-6ab0e3ac574606c46830ac02049d6facd60a0935
• ghcr.io/openclarity/vmclarity-plugin-kics-dev:pr1767-6ab0e3ac574606c46830ac02049d6facd60a0935
• ghcr.io/openclarity/vmclarity-ui-dev:pr1767-6ab0e3ac574606c46830ac02049d6facd60a0935
• ghcr.io/openclarity/vmclarity-ui-backend-dev:pr1767-6ab0e3ac574606c46830ac02049d6facd60a0935