requirements: missing setuptools

[cfriedt]

When I follow the instructions in the README file, I receive an error of the form:

$ progen build -t make_gcc_arm
Traceback (most recent call last):
  File "/home/cfriedt/FlashAlgo/venv/bin/progen", line 5, in <module>
    from project_generator.__main__ import main
  File "/home/cfriedt/FlashAlgo/venv/lib/python3.12/site-packages/project_generator/__main__.py", line 19, in <module>
    import pkg_resources
ModuleNotFoundError: No module named 'pkg_resources'

Steps to Reproduce:

On Ubuntu 24.04 (latest LTS release) with build-essential already installed

1. Download latest ARM GNU Toolchain
2. git clone https://github.com/mbedmicro/FlashAlgo && cd FlashAlgo
3. python3 -mvenv venv
4. source venv/bin/activate
5. pip install -r requirements.txt
6. progen build -t make_gcc_arm