Updates to CI workflow scripts

[lanctot]

• Github Actions migrate to node.js 20: upgrade version of checkout and upload-artifact to v4
• Remove (macos-11, Python3.8), add (macos-13, Python3.11)

[lanctot]

Waiting for later to move to macos-14, which uses Python 3.12.

See the error below, which occurred on macos-14: it also requires venv like most recent Linux distros.

Will do this in the upcoming Python 3.12 PR. This script should no longer be using get-pip.py. So, will have to modify the CI / install scripts.

++ python3 --version
Python 3.12.2
+++ which clang++
++ [[ -x /usr/bin/clang++ ]]
+++ which curl
++ [[ -x /usr/bin/curl ]]
++ [[ OFF == \O\N ]]
++ [[ OFF == \O\N ]]
++ curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed

  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
 67 2574k   67 1745k    0     0  14.9M      0 --:--:-- --:--:-- --:--:-- 14.9M
100 2574k  100 2574k    0     0  20.2M      0 --:--:-- --:--:-- --:--:-- 20.1M
++ python3 get-pip.py
error: externally-managed-environment

× This environment is externally managed
╰─> To install Python packages system-wide, try brew install
    xyz, where xyz is the package you are trying to
    install.
    
    If you wish to install a non-brew-packaged Python package,
    create a virtual environment using python3 -m venv path/to/venv.
    Then use path/to/venv/bin/python and path/to/venv/bin/pip.
    
    If you wish to install a non-brew packaged Python application,
    it may be easiest to use pipx install xyz, which will manage a
    virtual environment for you. Make sure you have pipx installed.

note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
hint: See PEP 668 for the detailed specification.