accessible_value: Fix errormessage relation layout

The type was recently changed because it was inconsistent within GTK.

See https://gitlab.gnome.org/GNOME/gtk/-/commit/649782b547aa837196344e3b2e51803ee94be74e

gtk4/src/accessible.rs

@@ -161,7 +161,7 @@ pub enum Relation<'r> {
     Controls(&'r [&'r Accessible]),
     DescribedBy(&'r [&'r Accessible]),
     Details(&'r [&'r Accessible]),
-    ErrorMessage(&'r Accessible),
+    ErrorMessage(&'r [&'r Accessible]),
     FlowTo(&'r [&'r Accessible]),
     LabelledBy(&'r [&'r Accessible]),
     Owns(&'r [&'r Accessible]),
@@ -202,7 +202,7 @@ impl<'r> Relation<'r> {
             Controls(v) => (AccessibleRelation::Controls, to_ref_list_value(v)),
             DescribedBy(v) => (AccessibleRelation::DescribedBy, to_ref_list_value(v)),
             Details(v) => (AccessibleRelation::Details, to_ref_list_value(v)),
-            ErrorMessage(v) => (AccessibleRelation::ErrorMessage, v.to_value()),
+            ErrorMessage(v) => (AccessibleRelation::ErrorMessage, to_ref_list_value(v)),
             FlowTo(v) => (AccessibleRelation::FlowTo, to_ref_list_value(v)),
             LabelledBy(v) => (AccessibleRelation::LabelledBy, to_ref_list_value(v)),
             Owns(v) => (AccessibleRelation::Owns, to_ref_list_value(v)),
@@ -301,7 +301,7 @@ mod tests {
             Relation::Controls(&[other1.upcast_ref(), other2.upcast_ref()]),
             Relation::DescribedBy(&[other1.upcast_ref(), other2.upcast_ref()]),
             Relation::Details(&[other1.upcast_ref(), other2.upcast_ref()]),
-            Relation::ErrorMessage(other1.upcast_ref()),
+            Relation::ErrorMessage(&[other1.upcast_ref()]),
             Relation::FlowTo(&[other1.upcast_ref(), other2.upcast_ref()]),
             Relation::LabelledBy(&[other1.upcast_ref(), other2.upcast_ref()]),
             Relation::Owns(&[other1.upcast_ref(), other2.upcast_ref()]),