Ubuntu 24.04 requires pipx for installing Conan

[leha-bot]

Due to the PEP(e)-668 and to avoid breakages with distro and pip packages, modern distros have become to require that Python libs must be installed using pipx. If the user tries to execute pip install (without --user flag), then they will get this error:

error: externally-managed-environment

x 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.