Thank you for your help. I am consistently using a conda virtual environment and installing everything by pip (into the same python environment), but I was bitten by the problem where one can install something using pip in the shell, but the version Jupyter sees is not updated. I must admit, I still confused by this. I removed mp-api and reinstalled it within Jupyter using the escape command
!{sys.executable} -m pip install <package_name>
I have mp-api version 0.35.1 installed and the example statement works fine.