Replace usage of deprecated apt-key

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

Author: vvoland

install-containerd-helpers

@@ -65,7 +65,7 @@ function install_debian_containerd() {
 	# Make sure ca-certificates are up-to-date
 	update-ca-certificates -f
 
-	curl -fsSL "${REPO_URL}/gpg" | apt-key add -
+	curl -fsSL "${REPO_URL}/gpg" | tee /etc/apt/trusted.gpg.d/containerd.gpg
 
 	if [ "${DIST_VERSION}" = "sid" ]; then
 		echo 'Debian sid ("unstable") cannot be used for packaging: replace with the actual codename'