Fix test that didn't compile.

blastmud_game/src/static_content/possession_type.rs

@@ -567,8 +567,15 @@ mod tests {
     #[test]
     fn every_improv_item_has_possession_data_for_output() {
         assert_eq!(
-            improv_table().iter().filter_map(|cd| if possession_data().get(&cd.output).is_none() { Some(cd) } else None ).collect(),
-            Vec::new()
+            improv_table()
+                .iter()
+                .filter_map(|cd| if possession_data().get(&cd.output).is_none() {
+                    Some(&cd.output)
+                } else {
+                    None
+                })
+                .collect::<Vec<&'static PossessionType>>(),
+            Vec::<&'static PossessionType>::new()
         );
     }
 }