feat: Add example of creating voice convo agent (#1962)

examples/sleeptime/voice_sleeptime_example.py

@@ -0,0 +1,32 @@
+from letta_client import Letta, VoiceSleeptimeManagerUpdate
+
+client = Letta(base_url="http://localhost:8283")
+
+agent = client.agents.create(
+    name="low_latency_voice_agent_demo",
+    agent_type="voice_convo_agent",
+    memory_blocks=[
+        {"value": "Name: ?", "label": "human"},
+        {"value": "You are a helpful assistant.", "label": "persona"},
+    ],
+    model="openai/gpt-4o-mini", # Use 4o-mini for speed
+    embedding="openai/text-embedding-3-small",
+    enable_sleeptime=True,
+    initial_message_sequence = [],
+)
+print(f"Created agent id {agent.id}")
+
+# get the group
+group_id = agent.multi_agent_group.id
+max_message_buffer_length = agent.multi_agent_group.max_message_buffer_length
+min_message_buffer_length = agent.multi_agent_group.min_message_buffer_length
+print(f"Group id: {group_id}, max_message_buffer_length: {max_message_buffer_length},  min_message_buffer_length: {min_message_buffer_length}")
+
+# change it to be more frequent
+group = client.groups.modify(
+    group_id=group_id,
+    manager_config=VoiceSleeptimeManagerUpdate(
+            max_message_buffer_length=10,
+            min_message_buffer_length=6,
+    )
+)