Fix: missing attribute finish() in curves selection code

Fixes a missing attribute `finish()` in the curves selection code.

Pull Request: https://projects.blender.org/blender/blender/pulls/114147

source/blender/editors/curves/intern/curves_selection.cc

@@ -84,6 +84,7 @@ bke::GSpanAttributeWriter ensure_selection_attribute(bke::CurvesGeometry &curves
     if (selection_attr.domain == selection_domain) {
       return selection_attr;
     }
+    selection_attr.finish();
     attributes.remove(".selection");
   }
   const int domain_size = attributes.domain_size(selection_domain);