Update poetry url for read the docs build.

.readthedocs.yaml

@@ -8,7 +8,7 @@ build:
   jobs:
     post_create_environment:
       # Install poetry
-      - curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py | python -
+      - curl -sSL https://install.python-poetry.org | python -
       # Tell poetry to not use a virtual environment
       - $HOME/.poetry/bin/poetry config virtualenvs.create false
       # Install project's dependencies