docs: try to fix The keys build.jobs and build.commands can't be used…

… together.

[skip ci]

.readthedocs.yaml

@@ -10,14 +10,10 @@ build:
   os: ubuntu-22.04
   tools:
     python: "3.11"
-  jobs:
-    post_create_environment:
-      - pip install poetry
-      - poetry config virtualenvs.create false
-    post_install:
-      - poetry install --with docs
   commands:
-    - mkdocs build --clean --site-dir $READTHEDOCS_OUTPUT/html --config-file mkdocs.yml
+    - pip install poetry
+    - poetry install --with docs
+    - poetry run mkdocs build --clean --site-dir $READTHEDOCS_OUTPUT/html --config-file mkdocs.yml
 
 mkdocs:
   configuration: mkdocs.yml