Install y-py >=0.5.4

Author: davidbrochart

.github/workflows/main.yml

@@ -46,6 +46,7 @@ jobs:
         pip install ./plugins/lab
         pip install ./plugins/jupyterlab
         pip install "jupyter_ydoc >=0.1.16,<0.2.0"  # FIXME: remove with next JupyterLab release
+        pip install "y-py >=0.5.4"
 
         pip install mypy pytest pytest-asyncio requests ipykernel