Pin Poetry verison in one more place.

.readthedocs.yaml

@@ -9,7 +9,7 @@ build:
     post_checkout:
       - git fetch --unshallow || true
     post_create_environment:
-      - python -m pip install poetry
+      - python -m pip install poetry==1.8.5
       - python -m poetry self add "poetry-dynamic-versioning[plugin]"
     post_install:
       - SKIP_PRE_BUILD=true VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH poetry install --with docs