voiceassistant: fix incomplete committed agent transcript in the chat_ctx (#595)

Author: theomonnom

.changeset/loud-pigs-explain.md

@@ -0,0 +1,5 @@
+---
+"livekit-agents": patch
+---
+
+voiceassistant: fix incomplete committed agent transcript in the chat_ctx

livekit-agents/livekit/agents/voice_assistant/agent_playout.py

@@ -161,8 +161,8 @@ def _should_break():
 
                 self.emit("playout_stopped", handle.interrupted)
 
-            handle._done_fut.set_result(None)
             await handle._tr_fwd.aclose()
+            handle._done_fut.set_result(None)
 
             logger.debug(
                 "playout finished",