Use --output=yaml instead of --short since that's deprecated, too

kubectl 1.25.4 bare `version` output says that `version --short` is
deprecated, but I missed the note that the output of `version --short`
will become the output of bare `version`. What's going away is what's
displayed by bare `version` presently. Since we probably still want the
long output in some form, let's dump it in YAML.

It's YAML all the way down, right?

cmd/vela-kubernetes/command.go

@@ -62,7 +62,7 @@ func versionCmd(c *Config) *exec.Cmd {
 	}
 
 	// add flag for version kubectl command
-	flags = append(flags, "version", "--short")
+	flags = append(flags, "version", "--output=yaml")
 
 	return exec.Command(_kubectl, flags...)
 }

cmd/vela-kubernetes/command_test.go

@@ -40,7 +40,7 @@ func TestKubernetes_versionCmd(t *testing.T) {
 		fmt.Sprintf("--context=%s", c.Context),
 		fmt.Sprintf("--namespace=%s", c.Namespace),
 		"version",
-		"--short",
+		"--output=yaml",
 	)
 
 	got := versionCmd(c)