v2.6.4

This release is a backport of OCI manifest fixes, and better support for cosign attestation download when you are using a mix of old Cosign signatures with the more recent bundle format. We strongly encourage folks to continue their migration to the bundle format. The Cosign v3.1.x releases support both formats; the primary change being that the default for signing is the bundle format (although you can specify –new-bundle-format=false to sign with the old format).