test: update test to handle rate limit error

Author: krrishdholakia

tests/image_gen_tests/test_image_generation.py

@@ -207,6 +207,8 @@ def test_image_generation_azure_dall_e_3():
         pass  # OpenAI randomly raises these errors - skip when they occur
     except litellm.InternalServerError:
         pass
+    except litellm.RateLimitError as e:
+        pass
     except Exception as e:
         if "Your task failed as a result of our safety system." in str(e):
             pass