fix Unable to validate cosign version: 'v2.0.0'

[casionone]

What is the purpose of the change

fix Unable to validate cosign version: 'v2.0.0'

Related issues/PRs

https://github.com/helm/chart-testing-action/issues/132

Checklist

• [x] I have read the Contributing Guidelines on pull requests.
• [ ] I have explained the need for this PR and the problem it solves
• [ ] I have explained the changes or the new features added to this PR
• [ ] I have added tests corresponding to this change
• [ ] I have updated the documentation to reflect this change
• [ ] I have verified that this change is backward compatible (If not, please discuss on the Linkis mailing list first)
• [ ] If this is a code change: I have written unit tests to fully verify the new behavior.