Fix CI Caching support

[Twon]

The Github Cache action is used to cache Conan dependencies during the build to avoid rebuilding them for each configuration.
Unfortunately this is unreliable at best, I believe as it's running into this issue: actions/cache#1561

The suggested solution is to migrate to: https://github.com/dawidd6/action-download-artifact

The feasibility of this should be investigated and the migration should be undertaken if workable.

[Twon]

https://stackoverflow.com/questions/70690760/how-to-use-dawidd6-action-download-artifact-with-pull-request-trigger