deb-update.bash: fix deprecated dnf alias

The manual page says "dnf update" is deprecated alias, current alias
would be "dnf up", but I guess in script using the actual command
"upgrade" is the best option.

bash/deb-update.bash

@@ -21,7 +21,7 @@ fi
 
 if hash dnf 2>/dev/null; then
     # If arguments like -y are passed to the script, they become "$@"
-    dnf "$@" update
+    dnf "$@" upgrade
 fi
 
 if hash flatpak 2>/dev/null; then