Installation into custom directory doesn't work when using setup.py

The documentation for PyCUDA tells to call `make install` after `configure.py` which then uses `python setup.py`

When installation into another directory than the base python installation folder is required, the created module cannot be imported in Python 3.8+ (at least)
Reason is that `python setup.py` creates an `egg` folder and a `pth` file, the latter is ignored, when outside of "site directories" so python doesn't search the egg folder and hence does not find pycuda.

A (common) use case are HPC modules, where Python is one module in one folder and (most) python libraries are separate modules each in an own folder. PYTHONPATH is then used to let python find that.

A solution is to simply use pip to install pycuda which creates a "proper" module installation