Missing CNI version inside Flannel conf

[obeyler]

As say in the specification of cni (https://github.com/containernetworking/cni/blob/master/SPEC.md#network-configuration)

https://github.com/jhunt/k8s-boshrelease/blob/2a771c749900d96fb5999314f80602fdcbffb6ae/jobs/net-flannel/templates/etc/cni/net.d/10-flannel.conflist#L2

example of config (see mandatory field: "cniVersion": "0.3.1")

{
    "name": "flannel-network",
    "cniVersion": "0.3.1",
    "plugins": [
        {
            "type": "flannel",
            "delegate": {
                "hairpinMode": true,
                "isDefaultGateway": true
            }
        },
        {
            "type": "portmap",
            "capabilities": {
                "portMappings": true
            }
        }
    ]
}

you can see the effect on missing cniVersion on this issue: https://github.com/containerd/containerd/issues/4012#issuecomment-589929358