In your README.md you write that a token does not need any scope.
In GitLab, when not selecting any scope, it seems to get all scopes but lets be as restrictive as possible.

I tried several scopes with role guest, but none worked.
I always get

INFO    -  git-committers: fetching contributors for docs/index.md
ERROR   -  git-committers: error fetching contributors for docs/index.md
ERROR   -  git-committers:   401 Unauthorized - You may have exceeded the API rate limit or need to be authorized. You can set a token under 'token' mkdocs.yml config or MKDOCS_GIT_COMMITTERS_APIKEY environment
           variable.

The scopes I tried (independently) are

• api
• read_api
• read_repository

Of course I always did a

export MKDOCS_GIT_COMMITTERS_APIKEY="<token>"

I am using mkdocs-material and set

plugins:
  - git-committers:
      repository: '<private repo slug>'
      branch: master

So what scope is actually required to get it working?