refactor(plugins): replace deprecated io/ioutil functions

The io/ioutil package has been deprecated as of Go 1.16 [1]. This commit
replaces the existing io/ioutil functions with their new definitions in
io and os packages.

[1]: https://golang.org/doc/go1.16#ioutil
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

plugins/network/triggers.go

@@ -2,7 +2,7 @@ package network
 
 import (
 	"fmt"
-	"io/ioutil"
+	"io"
 	"os"
 	"strings"
 
@@ -11,7 +11,7 @@ import (
 
 // TriggerDockerArgsProcess outputs the network plugin docker options for an app
 func TriggerDockerArgsProcess(appName string) error {
-	stdin, err := ioutil.ReadAll(os.Stdin)
+	stdin, err := io.ReadAll(os.Stdin)
 	if err != nil {
 		return err
 	}