Update languages.yml from source

When it comes to language detection for percentages in the repository, we use Linguist from GitHub.

Specifically, we extracted the language.yml from https://github.com/github/linguist/blob/master/lib/linguist/languages.yml back when @zj-gitlab removed the requirement for the actual Ruby gem.

This was last updated 2 years ago on the commit that removed that dependency: 399056ed.

Since we're no longer using and updating that gem, we're a little "behind" in language detection. Some users have noticed this in the form of:

• Issues with SQL dectection
• Tweet about missing Svelte detection
• Issues with XML detection

I believe just updating this will help elevate some of these issues, but it's unclear to me the relationship between GitLab and Gitaly here.