tmux: test for version before using new options

base/.tmux.conf

@@ -13,4 +13,7 @@ bind-key -n F3 previous-window
 bind-key -n F4 next-window
 
 set -s set-clipboard on
-set -g allow-passthrough on
+
+if-shell -b '[ "$(echo "$TMUX_VERSION >= 3.3" | bc)" = 1 ]' {
+    set -g allow-passthrough on
+}