chore(lints): fix compiler warnings and clippy array suggestions

src/scene/mod.rs

@@ -13507,7 +13507,7 @@ mod layout_cache_tests {
 
     #[test]
     fn cached_layout_names_returns_same_arc_until_bump() {
-        let mut scene = Scene::new();
+        let scene = Scene::new();
         let first = scene.cached_layout_names();
         let second = scene.cached_layout_names();
         assert!(std::sync::Arc::ptr_eq(&first, &second));

src/scene/pipeline/mod.rs

@@ -5949,7 +5949,7 @@ mod highlight_classification_tests {
 
     #[test]
     fn each_wire_lands_in_the_bucket_the_old_predicate_chose() {
-        let wires = vec![plain("1"), circle("2"), ellipse("3"), plain("4")];
+        let wires = [plain("1"), circle("2"), ellipse("3"), plain("4")];
         let refs: Vec<&WireModel> = wires.iter().collect();
         let depth_map = rustc_hash::FxHashMap::default();
 
@@ -5979,7 +5979,7 @@ mod highlight_classification_tests {
     // reach the instances.
     #[test]
     fn the_colour_override_reaches_the_instances() {
-        let wires = vec![circle("2"), ellipse("3")];
+        let wires = [circle("2"), ellipse("3")];
         let refs: Vec<&WireModel> = wires.iter().collect();
         let depth_map = rustc_hash::FxHashMap::default();