Code sections using old section tags

[jag1g13]

Code sections in this lesson (probably others too) are using the section tags from the old template - e.g. {: .python} instead of {: .language-python}.
This means they're not being syntax highlighted and the language isn't in the block title, they just say "Code".

See https://carpentries.github.io/lesson-example/04-formatting/index.html