Numpy is needed in the environment to run. You can choose to either create a
virtual environment or just install numpy globally.
```sh
sudo apt install python3-numpy
```
Create a Python virtual environment, install the dependencies in the virtual env
and point PYO3 to it:
```sh
python3 -m venv /tmp/iltcme
source /tmp/iltcme/bin/activate
pip install numpy
PYO3_PYTHON=/tmp/iltcme/bin/python cargo test
```