nanopb: Missing module in platformio library v 0.4.6

I receive an error when executing via pio run:

         *************************************************************
         *** Could not import the Google protobuf Python libraries ***
         *** Try installing package 'python3-protobuf' or similar.  ***
         *************************************************************

This can be remedied by running:

~/.platformio/penv/bin/pip3 install python3-protobuf

However it seems like this shouldn’t be necessary, or should at least be described in the installation instructions if it is.