Annotations module, which provides
vtkMRMLAnnotationRuler nodes have been deprecated since April 2021 and will be removed in Slicer-5.4 stable release (around early 2023).
all annotation nodes will be automatically converted to markup nodes when a scene is loaded
Starting in Slicer-5.3 preview releases (expected in a couple of weeks) Slicer will automatically convert annotation nodes to markup nodes to corresponding markup nodes when a scene is loaded.
Extensions that still use annotation nodes will have to be updated to use markup nodes before end of this year so that they continue to work with Slicer-5.4.
This section of the migration guide should help with implementing these changes, but we are happy to answer here any questions or help with any specific problems.