Fix missing namespace in OCI Repository Controller secret error

Include namespace in secret error message for better debugging context.
The secret name was already present in the error, but namespace information
was missing, making it harder to identify which secret in which namespace
was not found.

Signed-off-by: cappyzawa <cappyzawa@gmail.com>

internal/controller/ocirepository_controller.go

@@ -936,7 +936,7 @@ func (r *OCIRepositoryReconciler) keychain(ctx context.Context, obj *sourcev1.OC
 		if err != nil {
 			r.eventLogf(ctx, obj, eventv1.EventTypeTrace, sourcev1.AuthenticationFailedReason,
 				"auth secret '%s' not found", obj.Spec.SecretRef.Name)
-			return nil, err
+			return nil, fmt.Errorf("failed to get secret '%s': %w", secretRef, err)
 		}
 		imagePullSecrets = append(imagePullSecrets, imagePullSecret)
 	}