DevOps project updates - Githubissues

This PR updates the project structure, dependencies, benchmarks and library.

Specifically it:

Updates itertools, ordered_float and rstest
Blanket Time impls now require FloatCore due to updated ordered_float dependency
Benchmarks have been rewritten using criterion
rand has been moved to dev dependencies
.envrc has been removed and gitignored
License has been simplified to just MIT
There's new pre-commit config and Makefile which enable multiple new lints (e.g., cargo-deny)
Documentation has been updated and some typos fixed

matyama / makespan