GitHub actions are reliant on Ubuntu 20.04

[mhbardsley]

Issue

Issue #149 highlighted that there is currently a reliance on the Ubuntu 20.04 image to be used as a runner for GitHub actions. It is desirable to run on the latest Ubuntu image as GitHub will eventually remove support for Ubuntu 20.04, as they have done for 18.04. Some changes need to be made in order to facilitate pipelines on Ubuntu 22.04; it is not as simple as just changing the tag.

Expected behaviour

The GitHub Actions pipelines run successfully using the Ubuntu 22.04 image.

Actual behaviour

The GitHub Actions pipelines (test.yml, publish.yml, e2e.yml) fail with Ubuntu 22.04 as the runner (example).

Steps to reproduce

Fork this repository. Change the runs-on tag to ubuntu-22.04 or ubuntu-latest in one of the affected pipelines described above. Push this and run the associated pipeline. Inspect the result, which will likely be a Python or pip-related failure.