PySimpleGUI is missing

On fresh install `pysimplegui` module is missing. Documentation doesn't include it as dependency
```
$ ros2 launch as2_keyboard_teleoperation as2_keyboard_teleoperation_launch.py namespace:=drone0 use_sim_time:=true
[INFO] [launch]: All log files can be found below /home/parias/.ros/log/2023-06-19-15-02-49-649430-stealth15-26866
[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [as2_keyboard_teleoperation-1]: process started with pid [26867]
[as2_keyboard_teleoperation-1] Traceback (most recent call last):
[as2_keyboard_teleoperation-1] File "/home/parias/as2_ws/install/as2_keyboard_teleoperation/share/as2_keyboard_teleoperation/keyboard_teleoperation.py", line 41, in
[as2_keyboard_teleoperation-1] import PySimpleGUI as sg
[as2_keyboard_teleoperation-1] ModuleNotFoundError: No module named 'PySimpleGUI'
[ERROR] [as2_keyboard_teleoperation-1]: process has died [pid 26867, exit code 1, cmd 'python3 /home/parias/as2_ws/install/as2_keyboard_teleoperation/share/as2_keyboard_teleoperation/keyboard_teleoperation.py drone0 false true'].
```