Lightweight reproducible builds

[amiller]

This is a pretty simple repository, but it does rely on

The base gramine image is considered OK

Having to install build-essential seems to introduce a lot more system libraries that change and get included in the rust build

Lib-ssl is a dependency.

Maybe we just pin these specific dependency versions?

Should we try a tool like this?
https://github.com/reproducible-containers/repro-sources-list.sh

Would a split build image result in something better? Maybe building the rust library can be separated from running it so the runtime libraries are fewer.