Improve testing

I would like to collect here ideas on how to improve testing. This is my current non-exhaustive list
* run tests the library against multiple versions of Go
* run tests the library against multiple versions of platform (amd64, arm, arm64 and on linux, windows and macOS). We should run those tests for all platforms we declare to support
* Introduce code coverage
* Use go-fuzz for fuzzing GH #65
* Use only one docker container for interoperability testing: GH #157
* Build debian package - mainly to ensure any change to Makefile won't break Cloudflare's internal build. Also it would be great to be able to install go with tris from a package
* Introduce code coverage
* Benchmarking, to ensure there is no performance degradation (if that's possible)
* Can we do symbolic execution with something which has similar functionality to KLEE?

This issue is a collection of testing and build ideas rather than a single scoped task. Start by choosing one proposal, then review the referenced GH #65 and GH #157 discussions and the repository's existing test and build setup. Done should mean one selected improvement is implemented with a clear way to validate it.

Written by the indexing model from the issue text.