2nd-class support Julia #2689

Would pre-commit be open to supporting Julia as a first-class language? There's at least one project that Julia seem keen to have pre-commit support (JuliaFormatter.jl). I realized in attempting to provide pre-commit support that there's no first-class support for Julia.

I believe I'd be open to making a PR to provide said support, but wanted to ask if it's something pre-commit would be open to supporting, in the first place. 🙂