Pb 2295 GitHub actions

[PussInDasBoot]

• Github actions were failing as Python versions were no longer supported on the latest ubuntu build on actions
• Update the Github actions to install Anaconda3-2021.11 and install all dependencies as per the linux script.
• Cache these dependencies and other libraries required (openmpi-bin libopenmpi-dev libhdf5-dev) to speed up test runs in future)
• Remove Travis for CI as hasn't been used for 5 years

I removed the converagerc file as it was only including some directories to look at coverage for and excluding many others. I think it would be best to check coverage for the entire project. As I start increasing the coverage, I can build a new coveragerc if we feel it is necessary.

There are a lot of commits, but once this PR is approved and we're happy, I will squash and merge them.

[codecov-commenter]

Welcome to Codecov 🎉

Once you merge this PR into your default branch, you're all set! Codecov will compare coverage reports and display results in all future pull requests.

Thanks for integrating Codecov - We've got you covered ☂️

[geojunky]

Hi Melyn, I've suggested a few minor tweaks. We're almost there.

[geojunky]

Please add these requirements to conda_env_linux.sh as the final set of pip installs, so we can remove this requirements.txt altogether.