use bash for sketchybar aerospace plugin

.config/sketchybar/plugins/aerospace.sh

@@ -1,9 +1,10 @@
-#!/usr/bin/env zsh
+#!/usr/bin/env bash
 
 # Original source:
 #   https://nikitabobko.github.io/AeroSpace/goodness#show-aerospace-workspaces-in-sketchybar
 
-if (($argv[(Ie)$FOCUSED_WORKSPACE])); then
+# https://stackoverflow.com/a/47541882
+if printf '%s\0' "${argv[@]}" | grep -F -x -z -- "$FOCUSED_WORKSPACE"; then
     sketchybar --set "$NAME" label="$FOCUSED_WORKSPACE" background.drawing=on
 else
     sketchybar --set "$NAME" label="$FOCUSED_WORKSPACE" background.drawing=off