Add a sort_by and update deps

[aseigo]

This adds a sorty_by function as per a request on the Elixir discord server. It also updates the dependencies such that tests compile and work properly and docs are generated with a slightly more up-to-date version of ExDoc

[aseigo]

Four years on, will this ever get looked at? If not, would you @DanCouper consider handing over the maintainership of the library to someone who would maintain it going forward? Thanks.