highlight: fix codefence syntax in Hugo >= 0.121.0

[ehbauer]

With the latest version of the Relearn theme I ran into a strange problem that only happens in the Gitlab build of a Hugo project that uses the theme. The Gitlab setup is the easiest from the docs:

image: registry.gitlab.com/pages/hugo/hugo_extended:latest

variables:
  GIT_SUBMODULE_STRATEGY: recursive

pages:
  script:
    - hugo
  artifacts:
    paths:
      - public
  rules:
    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH

In one template I have some code snippets that specify a starting line number

```yaml {linenos=inline,linenostart=50}
# FINAL BUILD
FROM ubuntu-nginx-php:3.0.2-fpm8.2 AS prod
...

When building this fails with an error

Error: error building site: "/builds/nyyoy3xx/0/xxx/content/dev/boilerplate/docker/_index.md:149:1": execute of template failed: template: _default/_markup/render-codeblock.html:1:4: executing "_default/_markup/render-codeblock.html" at <partial "shortcodes/highlight.html" (dict "page" .Page "attributes" .Attributes "content" .Inner "options" .Options "type" .Type)>: error calling partial: "/builds/nyyoy3xx/0/xxxx/themes/relearn/layouts/partials/shortcodes/highlight.html:83:15": execute of template failed: template: partials/shortcodes/highlight.html:83:15: executing "partials/shortcodes/highlight.html" at <highlight $content $type $params>: error calling highlight: invalid Highlight option: linenostart

I couldn't really understand what the problem was and had to remove the linenostart specification for this to work. It is still mentioned in the docs and I don't see a relevant change in the highligh shortcode partial that would create the issue.

[McShelby]

I can't reproduce this. Without further information, your Hugo version might be outdated. The theme requires 0.112.4 at least.

[McShelby]

Seems to be an issue with Hugo 0.121. Or some change I yet have to discover. It's also not working without the theme's shortcode implementation (stock Hugo).

[McShelby]

Strange. I'll need to investigate. The plain Hugo new example works.

[McShelby]

Until this is fixed you could stay with the 0.120.x releases.

[ehbauer]

Thank you, this works. I dug into the 0.121 release notes but didn't see anything that could be relevant. There are no recently closed bugs that seem to relate to this. There is an open bug since 2021 that says this could relate to the Chroma lexer or fallback lexer gohugoio/hugo#8824

[ehbauer]

Correction, it does not run into an error but it also does not render the script block in 0.121. The element does not exist in the output; not even hidden, in its place there is no HTML code created. So, this has to be something that has existed longer and only now creates the error.

[McShelby]

This is now fixed. Something must have changed internally in Hugo. I suspect it's the new Go version.