Fixed to support Big Sur

[bergdahl]

Please check the README for more information on this change.

[lorol]

@bergdahl
Thank for submitting
I am not a fancy hygienic programmer. I am not a programmer at all, but I think on readme PR change you suggested me to merge, you (actually I may do the same mistake too) should not deviate the downloading of product of same work from somewhere else i.e your repository ... anyway.

[bergdahl]

Oh, sorry for the confusion - I only ment for you to merge the code changes and make a new release for download.
The changes for the README is just a note for for my friends that needed this fix fast.

[lorol]

Please remove these lines and resubmit

[lorol]

Readme.md
Line#8

[bergdahl]

Reverted README changes

[lorol]

The following error was fixed by @bergdahl

ValueError: dlsym(RTLD_DEFAULT, kIOMasterPortDefault): symbol not found

Changes

Changed the call to esptool to use the command python3 esptool.py instead as
newer versions of the esptool tool seems to be Python only. Python version 2 is obsolete but still default on macOS, which is why I used python3 to call the script.

If you done an in-place upgrade of macOS you also need to upgrade to the latest version of the pyserial package as well;

pip3 install --upgrade pyserial

In case you use newer boards like the ESP32S2, you may also need to upgrade the esptool.py file in the board support folder. You can find the existong file under a folder named like /Users/ -Your user Name- /Library/Arduino15/packages/esp32/tools/esptool_py/2.6.1. Just replace esptool.py with the latest one.

You can find the latest version of esptool here - https://github.com/espressif/esptool.