update install command (#16435)

.readthedocs.yaml

@@ -13,9 +13,14 @@ build:
     post_create_environment:
       - python -m pip install poetry
     post_install:
-      - VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH cd docs && poetry install
+      - cd docs && poetry config virtualenvs.create false && poetry install --no-root
     pre_build:
       - cd docs && poetry run merge-llama-deploy-docs
 
 mkdocs:
   configuration: docs/mkdocs.yml
+
+python:
+  install:
+    - method: pip
+      path: docs