refactor(configure): move OpenAI client initialization into function

This commit moves the initialization of the OpenAI client into the `default_model` function.
This change improves the code organization and ensures the client is only initialized when needed.
It should also eliminate OpenAI API key errors.

llamabot/cli/configure.py

@@ -7,8 +7,6 @@
 from .utils import configure_environment_variable
 
 
-client = OpenAI()
-
 app = typer.Typer()
 
 
@@ -46,6 +44,8 @@ def default_model(model_name=None):
 
     load_dotenv(llamabotrc_path)
 
+    client = OpenAI()
+
     model_list = client.models.list()
     available_models = [x.id for x in model_list if "gpt" in x.id]
     available_models.sort()