i3: More robust workspace json parsing

Use the name instead of the number as that could be -1.

.config/i3/config

@@ -101,7 +101,7 @@ workspace_auto_back_and_forth yes
 # Switch visible workspaces (e.g. multi monitor setup)
 bindsym $mod+Tab exec i3-msg workspace "$( \
 	i3-msg -t get_workspaces | \
-	jq '.[] | select(.visible and (.focused | not)).num' | \
+	jq -r '.[] | select(.visible and (.focused | not)).name' | \
 	head -1)"
 
 # move focused container to workspace