[Keyboard] add itstleo9 (#21460)

Co-authored-by: jack <0x6a73@protonmail.com>

keyboards/handwired/itstleo9/keymaps/default/keymap.c

@@ -0,0 +1,21 @@
+// Copyright 2023 QMK
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include QMK_KEYBOARD_H
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+    /*
+     * ┌───┬───┬───┐
+     * │ A │ B │ C │
+     * ├───┼───┼───┤
+     * │ D │ E │ F │
+     * ├───┼───┼───┤
+     * │ G │ H │ I │
+     * └───┴───┴───┘
+     */
+    [0] = LAYOUT_ortho_3x3(
+        KC_A,    KC_B,    KC_C,
+        KC_D,    KC_E,    KC_F,
+        KC_G,    KC_H,    KC_I
+    )
+};