[Fixes CI now!] ci: use venv for check

[casaroli]

Summary

To avoid the following CI error:

This environment is externally managed
--> To install Python packages system-wide, try apt install
    python3-xyz, where xyz is the package you are trying to
    install.

    If you wish to install a non-Debian-packaged Python package,
    create a virtual environment using python3 -m venv path/to/venv.
    Then use path/to/venv/bin/python and path/to/venv/bin/pip. Make
    sure you have python3-full installed.

    If you wish to install a non-Debian packaged Python application,
    it may be easiest to use pipx install xyz, which will manage a
    virtual environment for you. Make sure you have pipx installed.

    See /usr/share/doc/python3.12/README.venv for more information.

Impact

CI checks are fixed now

Testing

Check the logs.

[cederom]

Thank you @casaroli !! :-)

[cederom]

As in apache/nuttx#14176 this fixes the CI "build / fetch-source" worker error on nuttx-apps repo too :-)