fix it error

[ningmingxiao]

Signed-off-by: ningmingxiao [email protected]

openssl genrsa -out mykey.pem
openssl rsa -in mykey.pem -pubout -out mypubkey.pem
nerdctl image encrypt --recipient=jwe:mypubkey.pem  ghcr.io/stargz-containers/fedora:30-esgz test:encrypted

[root@LIN-FFF47298CDA ~]# nerdctl  inspect  --mode=native --format="{{len .Index.Manifests}}"  test:encrypted
FATA[0000] 1 errors: [Template parsing error: template: :1:12: executing "" at <.Index.Manifests>: map has no entry for key "Index"]