add deb-update.bash: apts, flatpak, snap

Why to have three different package managers with four different
commands to do a thing I am doing often, if I can script one command to
do it?

bash/deb-update.bash

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+set -x
+apt-get -y update
+apt-get "$@" upgrade
+flatpak update
+snap refresh
+set +x