Inconsistent Rust compiler version

[ximon18]

In the packaging workflow the version of the Rust compiler used depends on the workflow job being executed:

• For cross-compilation this is currently 1.64.0 from the Ubuntu 20.04 GitHub hosted runner pre-installed software.

• For O/S packaging it installs latest Rust via rustup.

• For Docker images it depends on how your Dockerfile performs the compilation.

This lack of consistency and control over the Rust version is not ideal, may cause confusing results, and may offer insufficient control for some use cases.

[ximon18]

FYI re cross compilation, the Rust version used at the time of writing in the GitHub Ubuntu 20.04 hosted runner image has since been bumped by Microsoft to Rust 1.73.0 per https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2004-Readme.md#rust-tools.