Setting up Python proved tricky for me. I solved the problem by using Docker:
docker pull rasa/rasa:1.10.1-full
# run the container as the current user (non-root)
alias rasa="docker container run --rm -it -v $(pwd):/app --user 1000:1000 rasa/rasa:1.10.1-full"
# now just use it
rasa init --no-prompt
rasa shell