Add required shellcheck to cleanup()

Signed-off-by: Richard Bonhomme <tincanteksup@gmail.com>

easyrsa3/easyrsa

@@ -328,6 +328,7 @@ easyrsa_mktemp() {
 # remove temp files and do terminal cleanups
 cleanup() {
 	[ -z "$EASYRSA_TEMP_DIR_session" ] || rm -rf "$EASYRSA_TEMP_DIR_session"
+	# shellcheck disable=SC2039
 	(stty echo 2>/dev/null) || { (set -o echo 2>/dev/null) && set -o echo; }
 	echo "" # just to get a clean line
 } # => cleanup()