Add --cleanup to `brew upgrade` bash completion

Closes Homebrew/homebrew#45075.

Signed-off-by: Baptiste Fontaine <batifon@yahoo.fr>

Library/Contributions/brew_bash_completion.sh

@@ -554,6 +554,7 @@ _brew_upgrade ()
         __brewcomp "
             --all
             --build-from-source --build-bottle --force-bottle
+            --cleanup
             --debug
             --verbose
             "