fix: replace requirements.txt files with poetry (4)

.readthedocs.yaml

@@ -7,9 +7,8 @@ build:
   jobs:
     post_create_environment:
       - pip install poetry
-      - poetry config virtualenvs.create false
     post_install:
-      - poetry install --with docs
+      - VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH poetry install --with docs
 
 sphinx:
   configuration: docs/conf.py