Avoid printing the error message twice from client

cmd/pinniped/cmd/root.go

@@ -4,7 +4,6 @@
 package cmd
 
 import (
-	"fmt"
 	"os"
 
 	"github.com/spf13/cobra"
@@ -22,7 +21,6 @@ var rootCmd = &cobra.Command{
 // This is called by main.main(). It only needs to happen once to the rootCmd.
 func Execute() {
 	if err := rootCmd.Execute(); err != nil {
-		fmt.Println(err)
 		os.Exit(1)
 	}
 }