update PyPI and spack repos

[TomMelt]

Now that there is a more stable version of mdb the following packages should be updated:

• [x] GitHub release - v1.0.4
• [x] PyPI - v1.0.4 has been uploaded
• [ ] spack

In addition, the spack recipe could use tidying up e.g., remove strict matplotlib req. and pip as runtime dep.