chore: add license headers (#384)

* feat: check for license headers

* add headers

* format

plugins/websocket/examples/svelte-app/src-tauri/build.rs

@@ -1,3 +1,7 @@
+// Copyright 2019-2023 Tauri Programme within The Commons Conservancy
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: MIT
+
 fn main() {
   tauri_build::build()
 }

plugins/websocket/examples/svelte-app/src-tauri/src/main.rs

@@ -1,3 +1,7 @@
+// Copyright 2019-2023 Tauri Programme within The Commons Conservancy
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: MIT
+
 #![cfg_attr(
   all(not(debug_assertions), target_os = "windows"),
   windows_subsystem = "windows"