Fix link checking in CI

[sdruskat]

• Introduce a workaround for link checking failing on docs.github.com URLs, see github docs return 403 gaurav-nelson/github-action-markdown-link-check#136 (comment).

Related issues

Fixes #425

Describe the changes made in this pull request

• Configure MLC to accept compressed reply enocdings for https://docs.github.com

Review checklist

• Please check if the pull request is against the correct branch
  (format/schema/semantic documentation changes: develop; typos, meta files, etc.: main)
• Please check if all changes are recorded in CHANGELOG.md and adapt if necessary.
• Please run tests locally.

cd $(mktemp -d --tmpdir cff.XXXXXX)
git clone https://github.com/citation-file-format/citation-file-format .
git checkout fix-link-checking
python3 -m venv env
source env/bin/activate
pip install --upgrade pip wheel setuptools
pip install -r requirements.txt
pytest
<do other things>

• Check if link checker in CI passes

[sdruskat]

Link checking now passes: https://github.com/citation-file-format/citation-file-format/actions/runs/3692831678/jobs/6252123110.

[jspaaks]

Nice, good to see the links checker workflow green. When I tried this out locally, I noticed 3 things:

1. I'd like to add a README.dev.md with technical stuff about the repo, how to set up tools, what the philosopy of testing/examples is, how to run the tests, how to run the link checker locally, how to prepare making a release, etc. I can't find this kind of information anywhere at the moment, probably because we had high hopes of keeping this repo small :).

2. some links in the schema-guide.md are incorrect (not due to this PR, but it seems it just went unnoticed so far), specifically I found problems with:

   npm install --save-dev markdown-link-check
   ./node_modules/markdown-link-check/markdown-link-check --progress README.md schema-guide.md
   
   # (some output omitted)
   
     178 links checked.
   
     ERROR: 3 dead links found!
     [✖] #yaml-strings → Status: 404      (page source suggests the anchor name is user-content-yaml-strings)
     [✖] #definitions.license-enum → Status: 404    (github removes dot from anchor)
     [✖] #definitioncountry → Status: 404    (definitions plural)
   

   Not sure why the link checker on GitHub didn't find these problematic.

3. The tool that gaurav/nelson uses (https://github.com/tcort/markdown-link-check) also comes as a pre-commit hook. We could add it to the repo and describe how to make use of it in README.dev.md

Let me know what you think of this, I can spawn issues as needed.

[sdruskat]

Closing as fixed in #424, spawned #446 and #447.