Missing support for Env

[twelvelabs]

Hello 👋, and thank you for the great extension!

I added the Env command to a VHS file today and it didn't get highlighted. Looks like there have been a few new commands added to https://github.com/charmbracelet/tree-sitter-vhs since your last release. Would you mind updating it?

FYI: Dependabot supports git submodules. I've used it before on projects to get notified about updates. Might want to consider setting it up.