install setuptools in unit tests workflow

Fix unit tests failing with Python 3.12 by installing setuptools package
explicitly. Since Python 3.12 ensurepip no longer provides setuptools,
and it's not installed by default in a virtual environment anymore.

https://docs.python.org/dev/whatsnew/3.12.html#ensurepip

.github/workflows/unit-tests.yml

@@ -50,6 +50,7 @@ jobs:
       run: |
         python3 --version
         python3 -m pip install --upgrade pip
+        pip3 install setuptools
         pip3 install -r requirements.txt
         pip3 list