Python 3.9.7 no longer supported

[rolyp]

GitHub Actions no longer supports 3.9.7.

• [x] bump Python locally to either 3.9.8 or 3.10.0
  • [x] conda install python=3.9.8 :x: version not available from current channels
  • [x] conda install python=3.9.10 :x: found conflicts (thousands of lines of error message)
  • [x] official Python 3.9.8 installer for MacOS :x: wasn't sure what it installed or where
  • [x] brew install python@3.9 :x: updates 3.9.7 to 3.9.7_1
  • [x] brew install python@3.9.8 :x: No available formula or cask with the name
  • [x] brew install python@3.10: already installed and up-to-date
  • poetry doesn't know how to find Python 3.10
  • [x] pyenv install 3.10.0
  • poetry doesn't know how to find Python 3.10
  • [x] pyenv install 3.9.8 :x: python-build: definition not found: 3.9.8
• [x] update pyproject.toml to 3.9.8
  • [x] poetry install doesn't bump Python version: manually delete .venv folder
  • [x] remove conda bullshit from .zshrc
• [x] bump notebooks to 3.9.8
• [x] bump GitHub Actions .yml file to 3.9.8
• [x] pin jsonschema to 3.2.0 to avoid altair-viz/altair/issues/2496