UV is not getting used when in an already active virtual environment

[NiklasRosenstein]

1. Run slap config --venv-type=UV
2. Create a new venv with UV and activate it
3. Run slap install in it (you need your CWD to be a Python project installable by Slap)
4. Notice how it tries to use Pip

It would also be good if it were able to detect the virtual environment type automatically.