Upgrade sphinx and related dependencies

[shahar1]

closes: #31963
related: #39449

This PR update the following dependencies:

• sphinx to v7+ (there's already v8, but it is supported only for Python 3.10)
• docutils to v0.21+ (haven't encountered any <section> tags as mentioned in the deleted inline comment)
• sphinx-autoapi to v3+ and astroid to v3+ (possible now that sphinx is v7+)
• sphinxcontrib-serializinghtml to v1.1.5+ (pinning it causes dependency conflicts)

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[shahar1]

Drafting, weirdly on v2-10-test it worked fine but here there are errors

[potiuk]

one more thing - last time when we tried to upgrade sphinx and docutils, the documentation looked ....weird .... lots of extra whitespace

[shahar1]

Apparently it is a quite a tough task, here are some insights:

• A requirement for upgrading Sphinx to v7 is to merge [BREAKING CHANGE] Update link tag for compatibility with Sphinx v7 airflow-site#1103 and create a new version for sphinx_airflow_theme (0.1.0). I struggled with mounting the changes locally, so for now, I made a workaround by injecting the contents of the file that was modified via Dockerfile.ci (created an issue for anyone who wants to tackle it in the future).

• When running only the build docs workflow, locally and on GitHub Actions, using breeze build-docs apache-airflow docker-stack --docs-only --clean-build, the build succeeds without any errors (see GitHub Action workflow). When running the docs server locally, the extra spaces issue indeed persists - we need to find out how to modify the related CSS (no success with it so far).
  

• When running only the spellchecks workflow, locally and on GitHub Actions, using breeze build-docs apache-airflow docker-stack --spellchecks-only --clean-build (see raw logs - BIG FILE warning) - we get a lot of weird errors. If you take a look at the logs, it often fails when parsing from /opt/airflow/providers/src/airflow/providers/amazon/aws/hooks/ssm.py::SsmHook:: get_parameter_value. Edit: it happened due to missing words in the spellcheck wordlist (see Update spelling wordlist #45579) - now it should be fine.

• When running the workflow for building docs and spelling altogether (breeze build-docs apache-airflow docker-stack --clean-build), the build fails due to a large number of implicit errors (which might be related to the failure of the spelling checks?).

• The MyPy workflow fails, but it doesn't seem too bad - in the worst case we just ignore it.

I'll be happy for some help in solving some of the riddles above, it will gets us closer to upgrading to Sphinx 7 :)

[potiuk]

#protm

[shahar1]

This change should be removed before merging

[shahar1]

Before merging, we should create a new version for sphinx-airflow-theme (0.1.0) after merging apache/airflow-site#1103