Tests and CI to add

[andreww]

The testing and CI need work. Some things to deal with:

• Tests that nail down the behaviour of PP.call() for out of bounds and vectorised calling and so on. Make sure we know and document what the right thing to do is because this function will need vectorisation and I'm not comfortable with my understanding of a vectorised version that Auggie has. May also want to compile some of this code for performance and I'm not sure I want to do that without tests!
• Tests for the behaviour of tabulating models. The behaviour of these functions (again, with a nice cleanup patch) is critical to having obspy and minios integration.
• Tests that we can run the notebooks! Somewhere I have code that can do this from the command line.
• Tests that we can run/link to obspy and minios. The last of these is likely to be difficult as we would need to install minios in a github runner - fortrantastic.
• For the CI, run the tests on pull requests. The triggers all need reworking.