Test aggregation when shapes touch but not overlap

[LucaMarconato]

Test the case when two squares (one in shapes and one in by) touch in a side or a vertex but not overlap.

For the overlay() case we will get the following warning:

/Users/macbook/embl/projects/basel/spatialdata/src/spatialdata/_core/operations/aggregate.py:427: UserWarning: `keep_geom_type=True` in overlay resulted in 1 dropped geometries of different geometry types than df1 has. Set `keep_geom_type=False` to retain all geometries
  overlayed = gpd.overlay(by, values, how="intersection")

The solution is to set keep_geom_type=True in overlay (currently is None, which behaves like keep_geom_type=True but gives a warning).

We need to check what currently happens in the sjoin() case.