Update README.md so it use python 3 instead of python 2

[JINODK]

Using python 3 instead of python 2 when installing pip, as it's EOL has been reached. https://www.python.org/doc/sunset-python-2 Also WSL only have python 3 shipped with it.

[JINODK]

Or maybe sudo apt purge python3 so WSL can install pyserial without conflict with the aready available python 3

[con-f-use]

Before you change the readme, did you check that things still work with py3?

[JINODK]

Just installed the Ubuntu 20.04 fresh from the store a few more times, found out that sudo apt-get install -y make gcc g++ gperf install-info gawk libexpat-dev python-dev python python-serial sed git unzip bash wget bzip2 libtool-bin dont actually install python2, nor sudo apt-get install -y make gcc g++ gperf install-info gawk libexpat-dev python-dev python2 python-serial sed git unzip bash wget bzip2 libtool-bin. Later found out that you can still use python3 with python2, but can still, in some case, somehow managed to screw up with 2 version at the same time, so maybe user can still keep python3. Also found out that WSL dont shipped with make installed. Fixed all of that problem with separate apt install from the rest: sudo apt install python2 make

[cnlohr]

I don't think this works the way you think it does? The flasher, esptool, the important thing, does not work with python3. I don't think this actually works... Most notably because of the python serial package which needs to specifically be for python 2.

[JINODK]

I found out that it cannot run with python 3 when recompiling after having created the pull request so i had revert it back to python 2, also WSL somehow does not install python(2) when apt get install with bunch of other program, so i have to install it separately from the rest, and the same goes for make too. Have to do sudo apt install python make separately.

[cnlohr]

If you still feel the current state of things is incorrect, can you create a new pull request? This has a bit more stacked history than I am comfortable with.