message: Fix Protobuf error message in CI
diff: @@ -49,4 +49,4 @@ pip install -U pip setuptools
  pip list --outdated --format=freeze | grep -v '^\-e' | cut -d = -f 1 | xargs -n1 pip install -U
  -pip install pytest-cov nbval
  +pip install pytest-cov nbval protobuf
  