Fix instancing example for hdr (#6554)

# Objective

- Using the instancing example as reference, I found it was breaking when enabling HDR on the camera. I found that this was because, unlike in internal code, this was not updating the specialization key with `view.hdr`.

## Solution

- Add the missing HDR bit.

examples/shader/shader_instancing.rs

@@ -116,11 +116,12 @@ fn queue_custom(
     let msaa_key = MeshPipelineKey::from_msaa_samples(msaa.samples);
 
     for (view, mut transparent_phase) in &mut views {
+        let view_key = msaa_key | MeshPipelineKey::from_hdr(view.hdr);
         let rangefinder = view.rangefinder3d();
         for (entity, mesh_uniform, mesh_handle) in &material_meshes {
             if let Some(mesh) = meshes.get(mesh_handle) {
                 let key =
-                    msaa_key | MeshPipelineKey::from_primitive_topology(mesh.primitive_topology);
+                    view_key | MeshPipelineKey::from_primitive_topology(mesh.primitive_topology);
                 let pipeline = pipelines
                     .specialize(&mut pipeline_cache, &custom_pipeline, key, &mesh.layout)
                     .unwrap();