fix(autogpt/llm): Omit AssistantChatMessage.tool_calls if no tool calls are present

OpenAI likes neither `tool_calls=[]` nor `tool_calls=None`. If no `tool_calls` are in the message, the key must be omitted.

This partially reverts commit 67bafa6302.

---

Co-authored-by: kcze <kpczerwinski@gmail.com>

autogpts/autogpt/autogpt/core/resource/model_providers/openai.py

@@ -423,7 +423,7 @@ class OpenAIProvider(
                 tool_calls=(
                     [AssistantToolCall(**tc.dict()) for tc in _assistant_msg.tool_calls]
                     if _assistant_msg.tool_calls
-                    else list()
+                    else None
                 ),
             )
             response = ChatModelResponse(
@@ -570,7 +570,10 @@ class OpenAIProvider(
             messages: list[ChatMessage], *_, **kwargs
         ) -> ChatCompletion:
             raw_messages = [
-                message.dict(include={"role", "content", "tool_calls", "name"})
+                message.dict(
+                    include={"role", "content", "tool_calls", "name"},
+                    exclude_none=True,
+                )
                 for message in messages
             ]
             return await self._client.chat.completions.create(

autogpts/autogpt/autogpt/core/resource/model_providers/schema.py

@@ -91,7 +91,7 @@ class AssistantToolCallDict(TypedDict):
 class AssistantChatMessage(ChatMessage):
     role: Literal["assistant"] = "assistant"
     content: Optional[str]
-    tool_calls: list[AssistantToolCall] = Field(default_factory=list)
+    tool_calls: Optional[list[AssistantToolCall]] = None
 
 
 class AssistantChatMessageDict(TypedDict, total=False):