tests: add python3.11 target in tox.ini file

[p-amok]

Hello, it would be great if berserk's tox.ini file supported the newly-released python3.11. Here is a PR for adding that support. For now all the requirements from requirements_dev.txt have been copied to a dedicated file, without the version limitations that immediately break the tests. I guess some other version restrictions are not recessary but they don't break the tests with python3.11.