refactor: move from io/ioutil to io and os package

The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

pkg/apparmor/apparmor_linux.go

@@ -17,7 +17,6 @@
 package apparmor
 
 import (
-	"io/ioutil"
 	"os"
 	"sync"
 )
@@ -36,7 +35,7 @@ func hostSupports() bool {
 	checkAppArmor.Do(func() {
 		// see https://github.com/opencontainers/runc/blob/0d49470392206f40eaab3b2190a57fe7bb3df458/libcontainer/apparmor/apparmor_linux.go
 		if _, err := os.Stat("/sys/kernel/security/apparmor"); err == nil && os.Getenv("container") == "" {
-			buf, err := ioutil.ReadFile("/sys/module/apparmor/parameters/enabled")
+			buf, err := os.ReadFile("/sys/module/apparmor/parameters/enabled")
 			appArmorSupported = err == nil && len(buf) > 1 && buf[0] == 'Y'
 		}
 	})