Fix config

See: https://github.com/getzola/zola/blob/master/CHANGELOG.md#breaking

Author: stackptr

config.toml

@@ -13,10 +13,9 @@ output_dir = "dist"
 
 theme = "anemone"
 
-[markdown]
-# Whether to do syntax highlighting
-# Theme can be customised by setting the `highlight_theme` variable to a theme supported by Zola
-highlight_code = true
+[markdown.highlighting]
+theme = "gruvbox-dark"
+error_on_missing_language = true
 
 [extra]
 header_nav = [