GHSA-77v3-r3jw-j2v2

### Summary The `getSecretKey` template function, while introduced for senhasegura Devops Secrets Management (DSM) provider, has the ability to fetch secrets cross-namespaces with the roleBinding of the external-secrets controller, bypassing our security mechanisms. This function was completely removed, as everything done with that templating function can be done in a different way while respecting our safeguards (for example, using `sourceRef` like explained here: https://github.com/external-secrets/external-secrets/issues/5690#issuecomment-3630977865) ### Impact - Cross-namespace secret access: Attackers or misconfigured resources could retrieve secrets from namespaces other than the one intended. - privilege escalation: Unauthorized access to secrets could lead to privilege escalation, data exfiltration, or compromise of service accounts and credentials. ### Resolution We removed the incriminated templating function from our codebase. All users should upgrade to the latest version containing this fix. ### Workarounds Use a policy engine such as Kubernetes, Kyverno, Kubewarden, or OPA to prevent the usage of `getSecretKey` in any ExternalSecret resource. ### Details See also: - https://github.com/external-secrets/external-secrets/issues/5690 - https://github.com/external-secrets/external-secrets/pull/3895