Get the metadata from the build method rather than object attribute

tests/test_metadata.py

@@ -79,8 +79,7 @@ def _sorted_constraints(constraints: set[Constraint]) -> list[Constraint]:
             schema = Schema.model_validate(self.yaml_data)
             schema.name = "main"
             builder = MetaDataBuilder(schema)
-            builder.build()
-            md = builder.metadata
+            md = builder.build()
 
             ctx = DatabaseContext(md, connection)