util.schema: fix geometry_classes_introduced_after using wrong IFC4X3 schema

It was passing `IFC4X3` directly to `schema_by_name` which is expecting
schema identifier (e.g. IFC4X3_ADD2, not IFC4X3 allowed by `IFC_SCHEMA`
- IFC4X3 is one of the IFC4X3 iterations while it was in development,
not the final one).

Noticed by tests failing:
FAILED
test/util/test_schema.py::TestGeometryClassesIntroducedAfter::test_ifc4x3_to_ifc2x3_is_superset_of_ifc4_to_ifc2x3
- RuntimeError: No schema named IFC4X3
FAILED
test/util/test_schema.py::TestGeometryClassesIntroducedAfter::test_ifc4_to_ifc4x3_is_empty
- RuntimeError: No schema named IFC4X3

src/ifcopenshell-python/ifcopenshell/util/schema.py

@@ -175,8 +175,8 @@ def geometry_classes_introduced_after(target_schema: IFC_SCHEMA, source_schema:
     B-splines, advanced surfaces, alignment curves on IFC4X3 → 2X3, …) or
     purge. Defaults match the IFC4 → IFC2X3 case for backwards compatibility
     with the original caller."""
-    source = ifcopenshell_wrapper.schema_by_name(source_schema)
-    target = ifcopenshell_wrapper.schema_by_name(target_schema)
+    source = ifcopenshell.schema_by_name(source_schema)
+    target = ifcopenshell.schema_by_name(target_schema)
     target_names = {decl.name() for decl in target.entities()}
     result: set[str] = set()
     for decl in source.entities():