Fix map object is not subscriptable in version.py

[Doreapp]

Hi,
While upgrading to 21.03 branch, I encountered an error linked to the $(shell ./verision.py 21.03) Makefile's first line.
(map object is not subscriptable).
It should be linked to python3 usage.

I fixed it, replacing line 21 of version.py from

main(map(int, sys.argv[1].split('.')) if len(sys.argv) == 2 else None)

to

main([int(i) for i in sys.argv[1].split('.')] if len(sys.argv) == 2 else None)

(as suggested fix in this SO answer)

I post it as a workaround for people encountering the same error, and maybe improvement for further releases.