Fix rate limit problem of the render action

[nuest]

See https://github.com/codecheckers/register/actions/runs/11251093376/job/31281384845

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https://docs.github.com/en/rest/using-the-rest-api/rate-limits-for-the-rest-api says

The primary rate limit for unauthenticated requests is 60 requests per hour.

So that is way to little.

You can use a personal access token to make API requests. Additionally, you can authorize a GitHub App or OAuth app, which can then make API requests on your behalf.
All of these requests count towards your personal rate limit of 5,000 requests per hour.

That should be fine.

For the same reason, I cannot even render the register locally anymore using the Docker image, i.e., make image_render in.

https://docs.github.com/en/actions/security-for-github-actions/security-guides/automatic-token-authentication#using-the-github_token-in-a-workflow seems to have a suitable solution for the GitHub Action. From the previous link:

You can use the built-in GITHUB_TOKEN to authenticate requests in GitHub Actions workflows. See "Automatic token authentication."
The rate limit for GITHUB_TOKEN is 1,000 requests per hour per repository.

We also need documentation on using a token for the local rendering then with the image.