In the October 2023 update of ArcGIS Online, we released the 9.0 version of the notebook runtimes, including the latest ArcGIS API for Python 2.2.0 and other Python packages.
A manifest of the Python packages and versions included in the 9.0 runtime will be available on https://www.esri.com/en-us/arcgis/products/arcgis-notebooks/runtime-manifests in November 2023.
In the meantime, you can check all installed packages in a notebook environment using one of the following methods:
1. Check installed packages from the "Info" tab of a notebook.
2. Check installed packages with `conda list`.
!conda list
and the cell will output a list of installed packages in the current environment.
See graphic below for more details.
Update: here is a link to the PDF.