Cleanup examples and fix VoicesManager types (#332)

Signed-off-by: rany <rany2@riseup.net>

examples/async_audio_gen_with_predefined_voice.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+
+"""Simple example to generate audio with preset voice using async/await"""
+
+import asyncio
+
+import edge_tts
+
+TEXT = "Hello World!"
+VOICE = "en-GB-SoniaNeural"
+OUTPUT_FILE = "test.mp3"
+
+
+async def amain() -> None:
+    """Main function"""
+    communicate = edge_tts.Communicate(TEXT, VOICE)
+    await communicate.save(OUTPUT_FILE)
+
+
+if __name__ == "__main__":
+    asyncio.run(amain())