update contrib

CONTRIBUTING.md

@@ -8,25 +8,23 @@ You may follow these steps if you wish to create a pull request. Fork the repo a
 in the project's directory run this if you're on macOS (requires [Homebrew](https://brew.sh)):
 
 ```bash
-brew install python@3.7
+brew install python
 brew install poetry  # More info: https://python-poetry.org
 make clean
-POETRY_VIRTUALENVS_IN_PROJECT=true poetry env use "$(brew --prefix)/opt/python@3.7/bin/python3"
 ```
 
 On Ubuntu (including Windows WSL2):
 
 ```bash
-sudo apt-get update && sudo apt-get install make python3-virtualenv python3.9
-curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/install-poetry.py | python3 -
+sudo apt-get update && sudo apt-get install make python3-virtualenv python3
+curl -sSL https://install.python-poetry.org | python3 -
 make clean
-POETRY_VIRTUALENVS_IN_PROJECT=true poetry env use "$(which python3.9)"
 ```
 
 Then see if you can run lints and tests:
 
 ```bash
-make all
+make deps all
 ```
 
 ## Writing Tests