chore: add caching to Linux docker run

[stevenh]

Add cache mount directives to Linux docker container so that reruns are much quicker.

[mdelapenya]

Hey @stevenh what are the motivation for this PR? Do you think it makes a real difference with the current state of the release process?

IIUC this will happen at build time of Ryuk, which is done just once per release. I see the benefits of building a Docker image faster, but want to check with you the implications/importance of this update.

Thanks!

[stevenh]

For the release process no benefit. For the developer working on this it was much quicker iteration time, which was the motivation.