Request for testers: Gleam support in Mix

@Papipo I’m running at the latest version; it’s working fine now. Pretty good actually, given I’m testing it with a local Gleam dependency imported inside an umbrella app (something that was not viable just with the mix_gleam). Super happy with it! It might allow me to have a shot at my company adopting Elixir :smiley: Thanks lot for working on this!

The only small side effect I found is that when I run compilation from scratch, I normally get an ** (Mix) Unknown dependency <some dep> for environment dev error at the first run, but if I try again, it just works fine.

Amazing!

I am going to change how the .app file is generated and this should also fix the double-compilation issue.