Python environment upgrade

• Commit all your changes on your local branch
• Switch to master branch
• Close Pycharm
• Start Anaconda Prompt (Windows) or Terminal (MacOS)
• Go to the TLOmodel directory (e.g. Documents/PycharmProjects/TLOmodel)
• conda create -n tlo38 python=3.8
• Press 'y' to proceed
• conda activate tlo38
• pip install -r requirements/dev.txt
• pip install -e .
• pytest tests/test_basic_sims.py
• Start Pycharm
• Switch environment to use tlo38
• Switch back to your working branch and merge master into current