Tests fail upon fresh install.

Upon following the instructions to setup a development environment, i.e:

```bash
git clone https://github.com/google/jax-cfd; cd jax-cfd
python -m venv venv
source venv/bin/activate
pip install --upgrade pip
pip install jaxlib
pip install -e ".[complete]"
```

and running the test suite, as per:

```bash
python -m pytest -n auto jax_cfd --dist=loadfile --ignore=jax_cfd/base/validation_test.py
```

the test-suite fails with:

```bash
11 failed, 447 passed, 242 warnings, 4 errors
```

I've attached a full output of the tests [**here**.](https://gist.github.com/danielkelshaw/8911674fbbbbec1676191874eaacc3e3)

**Quick note on running tests:** the instructions in the `README.md` don't run if you set the environment up like I did above. The modification with `python -m` prefixing the command is required.

Are there any plans to fix these to ensure that all tests pass?