Allow setting OpenAI model in settings

fern/docs/pages/manual/llms.mdx

@@ -38,6 +38,8 @@ llm:
 
 openai:
   api_key: <your_openai_api_key>  # You could skip this configuration and use the OPENAI_API_KEY env var instead
+  model: <openai_model_to_use> # Optional model to use. Default is "gpt-3.5-turbo"
+                               # Note: Open AI Models are listed here [here](https://platform.openai.com/docs/models)
 ```
 
 And run PrivateGPT loading that profile you just created:

private_gpt/components/llm/llm_component.py

@@ -53,7 +53,9 @@ def __init__(self, settings: Settings) -> None:
             case "openai":
                 from llama_index.llms import OpenAI
 
-                openai_settings = settings.openai.api_key
-                self.llm = OpenAI(api_key=openai_settings)
+                openai_settings = settings.openai
+                self.llm = OpenAI(
+                    api_key=openai_settings.api_key, model=openai_settings.model
+                )
             case "mock":
                 self.llm = MockLLM()

private_gpt/settings/settings.py

@@ -154,6 +154,10 @@ class SagemakerSettings(BaseModel):
 
 class OpenAISettings(BaseModel):
     api_key: str
+    model: str = Field(
+        "gpt-3.5-turbo",
+        description=("OpenAI Model to use. Example: 'gpt-4'."),
+    )
 
 
 class UISettings(BaseModel):

settings.yaml

@@ -49,3 +49,4 @@ sagemaker:
 
 openai:
   api_key: ${OPENAI_API_KEY:}
+  model: gpt-3.5-turbo