update dependencies & replace deprecated list.concat

[bwireman]

Hi love birdie and all the contributions you've made to gleam! Wanted to go ahead and update some deps and deprecated functions after I started seeing build and lint warnings in my go_over project after adding birdie and updating the stdlib

My changes in go-over: https://github.com/bwireman/go-over/commit/4488f736befc6cc1935ec816f6971b82ff0ac5bd#diff-7cd1e07e743a743d849d706b1dafd77e5839325c3b7327d3f060335605d525beR54

stdlib change: https://hexdocs.pm/gleam_stdlib/gleam/list.html#concat

Let me know if you want me to make changes or just close the MR!

[giacomocavalieri]

Thank you!!