Docker build script for Window uses outdated Python version

[bitsgalore]

The docker-package-win.sh uses cdrx/pyinstaller-windows, which is based on a very old (3.7) Python version.

[bitsgalore]

Forks of cdrx/pyinstallerwindows:

https://github.com/cdrx/docker-pyinstaller/forks

Diff between last cdrx version and Bart Broere's fork:

cdrx/docker-pyinstaller@master...bartbroere:docker-pyinstaller:master

[bitsgalore]

Created a new fork of cdrx/pyinstallerwindows (work in progress):

https://github.com/bitsgalore/docker-pyinstaller