Update github actions to their latest version

[stof]

This avoids using the deprecated node 12.x runtime.

[orta]

All of these have the node version defined as 14 (you can see in the diff) -- the changes are probably harmless though

[stof]

I'm not talking about the version of node installed with setup-node, but about the runtime used by the actions themselves: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/

[orta]

Great, makes sense to me - thanks