Debian testing and virtual environment error message

[songbird]

songbird wrote:
...
>   The package mentioned is installed:
>
>
>=====
>
> $ dpkg -l | grep python3-venv
> ii  python3-venv                         3.9.0-4                        amd64        pyvenv-3 binary for python3 (default python3 version)
>

  here is something i missed including in my first post, but i don't
know if this matters:

ii  python3.9-venv                       3.9.1-1                        amd64        Interactive high-level object-oriented language (pyvenv binary, version 3.9)


  songbird