versioning: plugins require version match with config

infer version 0.1.0 when config is missing an explicit "cniVersion" field

pkg/version/plugin.go

@@ -59,7 +59,7 @@ func PluginSupports(supportedVersions ...string) PluginInfo {
 // PluginDecoder can decode the response returned by a plugin's VERSION command
 type PluginDecoder struct{}
 
-func (_ *PluginDecoder) Decode(jsonBytes []byte) (PluginInfo, error) {
+func (*PluginDecoder) Decode(jsonBytes []byte) (PluginInfo, error) {
 	var info pluginInfo
 	err := json.Unmarshal(jsonBytes, &info)
 	if err != nil {