#165, #182: Stop using the Makefile in the CI and tools installed from Poetry dev dependencies in favor of pre-commit, Bump Sphinx to v4

• Simplify the commands to build the documentation
• Remove the dev dependencies now used as pre-commit hooks
• Bump Sphinx to v4.3.0
• Makefile: Update commands, since it wasn’t maintained
• Readme: Update make commands accordingly

The documentation is building correctly, tested in this job.

Close #165 (closed), #182 (closed).

.gitlab-ci.yml

@@ -147,13 +147,13 @@ pages:
   stage: publish_doc
   script:
     - poetry install
-    - make docs
-    - mv docs/_build/html public
-    - ls public
+    - poetry run sphinx-apidoc -o docs .
+    - poetry run sphinx-build -b html docs public
   artifacts:
     untracked: true
     paths:
       - public
+    expire_in: 2 days
   rules:
     - if: $CI_COMMIT_TAG
       when: manual