CI: Enable clippy on Windows (#8240)

Release Notes:

- N/A

crates/gpui/src/platform/test/platform.rs

@@ -126,8 +126,9 @@ impl Platform for TestPlatform {
         #[cfg(target_os = "macos")]
         return Arc::new(crate::platform::mac::MacTextSystem::new());
 
+        // todo!("windows")
         #[cfg(target_os = "windows")]
-        todo!("windows")
+        unimplemented!()
     }
 
     fn run(&self, _on_finish_launching: Box<dyn FnOnce()>) {