fix readthedocs

.readthedocs.yml

@@ -3,12 +3,14 @@ version: 2
 build:
   os: ubuntu-22.04
   tools:
-    python: "3.11"
+    python: "3.12"
   jobs:
-    post_install:
+    post_create_environment:
       - pip install poetry
-      - poetry config virtualenvs.create false
-      - poetry install --with=docs
+    post_install:
+      # VIRTUAL_ENV needs to be set manually for now.
+      # See https://github.com/readthedocs/readthedocs.org/pull/11152/
+      - VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH poetry install --with docs
 
 sphinx:
   configuration: docs/source/conf.py