Fix the Poetry install command for Read the Docs

We don’t need `--with-docs`.

Author: remcohaszing

.readthedocs.yaml

@@ -7,7 +7,7 @@ build:
   jobs:
     post_install:
       - pip install poetry
-      - VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH poetry install --with docs
+      - VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH poetry install
 
 sphinx:
   configuration: docs/conf.py