* optimise unit tests - Cache loading the config TOML
Unit test time: 13.1s -> 10.5s
* optimise unit tests - use the same pyproject validator across the tests
Unit test time: 10.5s -> 5.7s
* optimise unit tests - selector optimisation
Unit test time: 5.7s -> 5.1s
* optimise unit tests - build options computation cache
Unit test time: 5.1s -> 3.2s
* Use functools.cache rather than functools.lru_cache
* Don't overwrite build_options when applying functools.cache
Joe Rickerby
c136aefe20