Fix compilation of integration example in release mode

Fixes iced-rs#2447.

Author: hecrj

examples/integration/Cargo.toml

@@ -8,7 +8,9 @@ publish = false
 [dependencies]
 iced_winit.workspace = true
 iced_wgpu.workspace = true
+
 iced_widget.workspace = true
+iced_widget.features = ["wgpu"]
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 tracing-subscriber = "0.3"