Unable to install latest textual and rich-cli together

[claviola]

Since rich-cli pins textual to 0.1.18 it's not possible to install Textual as suggested in the README:

$ pip install --index-url=https://pypi.org/simple "textual[dev]"
Defaulting to user installation because normal site-packages is not writeable
Requirement already satisfied: textual[dev] in ./.local/lib/python3.7/site-packages (0.1.18)
  WARNING: textual 0.1.18 does not provide the extra 'dev'
Requirement already satisfied: rich<13.0.0,>=12.3.0 in ./.local/lib/python3.7/site-packages (from textual[dev]) (12.6.0)
$ python -m textual
python: No module named textual.__main__; 'textual' is a package and cannot be directly executed