Proposed fix for non-recognized holes

When the geometries resulting from an operation result in a MultiPolygon that only touch at points, a hole is not recognized in shapely but it is "recognized" by humans. To fix this problem, the hole needs to be recognized by shapely as part of a Polygon. One solution to fix this would be to buffer the geometry by a very small amount to force this switch from MultiPolygon to Polygon.

src/sectionproperties/pre/geometry.py

@@ -2384,7 +2384,10 @@ def compile_geometry(self) -> None:
         # Determine if new holes have been created or if existing
         # holes have been destroyed (or "filled in").
         resultant_holes = []
+        SCALE_CONSTANT = 1e-9
         unionized_poly = unary_union([geom.geom for geom in self.geoms])
+        buffer_amount = unionized_poly.area * SCALE_CONSTANT
+        unionized_poly = unionized_poly.buffer(buffer_amount)
 
         if isinstance(unionized_poly, MultiPolygon):
             for poly in unionized_poly.geoms: