chore: update wgpu to v26 (#39016)

Vello has updated to wgpu v26 recently. It might be a good time for
servo to update as well. This PR should wait for #39015 and #38717

Testing: WebGPU CTS
Fixes: None

---------

Signed-off-by: Wu Yu Wei <yuweiwu@pm.me>

components/script/dom/webgpu/gpucommandencoder.rs

@@ -197,6 +197,7 @@ impl GPUCommandEncoderMethods<crate::DomTypeHolder> for GPUCommandEncoder {
                     ),
                     store_op: color.storeOp.convert(),
                     view: color.view.id().0,
+                    depth_slice: None,
                 }))
             })
             .collect::<Fallible<Vec<_>>>()?;