fix silent LaTeXString conversion

[t-bltg]

Description

Fix #2513.

In OP's bug report, the LaTeXString was silently converted to a String, resulting in $ signs appearing in the Axis3D case.

Type of change

Delete options that do not apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• Added an entry in NEWS.md (for new features and breaking changes)
• Added or changed relevant sections in the documentation
• Added unit tests for new algorithms, conversion methods, etc.
• Added reference image tests for new plotting functions, recipes, visual options, etc.

[ffreyer]

The test failure is just a communication error so this should be good to go right?

Error: Resource not accessible by integration

[t-bltg]

No, this needs new reference images merged (label type change test), expanding Run mshick/add-pr-comment@v1 yields:

Run mshick/add-pr-comment@v1
  with:
    message: ## Missing reference images
  Found 1 new images without existing references.
  Upload new reference images before merging this PR.

    repo-token: ***
    allow-repeats: true
  env:
    MODERNGL_DEBUGGING: true
    ARTIFACTS_PATH: ~/.julia/artifacts
    PACKAGES_PATH: ~/.julia/packages
    REGISTRIES_PATH: 
    PRECOMPILATION_CACHE_PATH: 
    TESTS_SUCCESSFUL: true
Error: Resource not accessible by integration

[asinghvi17]

I think there are a couple of new reference tests in this round of PRs, Simon mentioned he usually uploads those manually.

[t-bltg]

IIUC, this can only be done by contributors with write access (which I don't have).

[asinghvi17]

True - I meant that AFAIK Simon himself uploads those manually, after merging a bunch of PRs. CC @SimonDanisch - is this good to merge?

[github-actions]

Missing reference images

Found 1 new images without existing references.
Upload new reference images before merging this PR.