include Julia

[ilia-kats]

Please consider including the Julia language in the image. I have set up the pre-commit.ci app on a Julia repository with the JuliaFormatter hook, but I'm getting Executable 'julia' not found in the pre-commit.ci results.

[asottile]

definitely want to include julia! would you be interested in contributing a patch to the dockerfile to add it: https://github.com/pre-commit-ci/runner-image/blob/main/Dockerfile

plus a small test here: https://github.com/pre-commit-ci/runner-image/blob/main/bin/test