add openai:o1 model support (#498)

Author: sydney-runkle

pydantic_ai_slim/pydantic_ai/models/__init__.py

@@ -31,6 +31,7 @@
     'openai:gpt-4',
     'openai:o1-preview',
     'openai:o1-mini',
+    'openai:o1',
     'openai:gpt-3.5-turbo',
     'groq:llama-3.3-70b-versatile',
     'groq:llama-3.1-70b-versatile',