Change "python" to "python3"

[tomorrow56]

First aid for ESP32 builds not passing in Arduino IDE on macOS Monterey 12.3 that obsolete "python2.7".

By completing this PR sufficiently, you help us to improve the quality of Release Notes

Checklist

1. Please provide specific title of the PR describing the change, including the component name (eg. „Update of Documentation link on Readme.md“)
2. Please provide related links (eg. Issue, other Project, submodule PR..)
3. Please check Contributing guide

This entire section above can be deleted if all items are checked.

---

Summary

Please describe your proposed PR and what it contains.

Impact

Please describe impact of your PR and it's function.

Related links

Please provide links to related issue, PRs etc.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[Jason2866]

Since python 2.7 is totally outdated and should be used nowhere this change is not needed.
It is standard that python calls a version which is 3.x
So Apple has missed something... The change is needed there
Btw. i use Apple Monterey 12.3. too. I did the easy needed change there

[Xylopyrographer]

@Jason2866 Hi. Just did the update to macOS 12.3 Can't link anything under Arduino IDE 1.8.19 as it now reports:
exec: "python": executable file not found in $PATH

What did you do to make this a go again?

From Terminal, running which python (and all variants like python3, etc.) returns python not found.

[Jason2866]

@Xylopyrographer Best way is to install via homebrew. A tutorial is here

[rin67630]

IIMHO at least on Mojave the Arduino IDE still has flaws.

You need to add the path to Python3 manually, reboot AND you must call the Arduino IDE from the terminal open /Applications/Arduino.app to be able to compile for the ESP32...
Not very handy, I think.