Use consistent bash5 style for conditionals and quoting

bin/omarchy-update-restart

@@ -1,13 +1,13 @@
 #!/bin/bash
 
-if [ ! -d "/usr/lib/modules/$(uname -r)" ]; then
+if [[ ! -d /usr/lib/modules/$(uname -r) ]]; then
   gum confirm "Linux kernel has been updated. Reboot?" && omarchy-cmd-reboot
-elif [ -f "$HOME/.local/state/omarchy/reboot-required" ]; then
+elif [[ -f $HOME/.local/state/omarchy/reboot-required ]]; then
   gum confirm "Updates require reboot. Ready?" && omarchy-cmd-reboot
 fi
 
 for file in "$HOME"/.local/state/omarchy/restart-*-required; do
-  if [ -f "$file" ]; then
+  if [[ -f $file ]]; then
     filename=$(basename "$file")
     service=$(echo "$filename" | sed 's/restart-\(.*\)-required/\1/')
     echo "Restarting $service"