esptool.py should be ran by python3, not python2

[FilipDominec]

Describe the bug
On newer Ubuntu (Focal Fossa), it is not easy to install the pyserial module anymore for python2. The repository has pyserial for python3 only. Therefore, this dependency of esptool.py for python2 is missing on most systems.

Desktop (please complete the following information):

• OS: Ubuntu
• Version: Focal Fossa, 20.04

Quick & dirty fix
Actually, esptool.py seems to run with Python3.

Since the upload command may be hard-coded in Arduino IDE, a small change can be made to switch the python interpreter:

1. go to .arduino15/packages/esp32/tools/ and rename esptool.py to real_esptool.py

2. in the same directory, create a file esptool.py with the following contents:

   import subprocess, sys
   subprocess.call("python3 ./real_esptool.py " + " ".join(sys.argv[1:]), shell=True)

3. run the arduino studio like before; it should be able to upload now

[per1234]

Hi @FilipDominec. Thanks for your interest in this open source project.

esptool and the choice of which Python interpreter to use is purely a matter of the 3rd party ESP32 boards platform's configuration. The Arduino IDE (or more accurately, Arduino CLI) only provides the framework that runs the compilation and upload processes according to the dictates of the platform configuration of the currently selected board. So this is not anything that can be managed from the code base hosted in this repository. It would be something to be done in the ESP32 boards platform repository, which is not maintained by the Arduino organization:
https://github.com/espressif/arduino-esp32

[FilipDominec]

@per1234 thanks for info, I reported it here: espressif/arduino-esp32#4717