fix(factory.py): flexible handling of image file type in b64 encode

Fixes https://github.com/BerriAI/litellm/issues/4589

litellm/tests/test_completion.py

@@ -848,6 +848,45 @@ def test_completion_function_plus_image(model):
     print(response)
 
 
+@pytest.mark.parametrize(
+    "model", ["gemini/gemini-1.5-pro"]  # "claude-3-sonnet-20240229",
+)
+def test_completion_function_plus_pdf(model):
+    litellm.set_verbose = True
+    try:
+        import base64
+
+        import requests
+
+        # URL of the file
+        url = "https://storage.googleapis.com/cloud-samples-data/generative-ai/pdf/2403.05530.pdf"
+
+        # Download the file
+        response = requests.get(url)
+        file_data = response.content
+
+        encoded_file = base64.b64encode(file_data).decode("utf-8")
+
+        image_content = [
+            {"type": "text", "text": "What's this file about?"},
+            {
+                "type": "image_url",
+                "image_url": {"url": f"data:application/pdf;base64,{encoded_file}"},
+            },
+        ]
+        image_message = {"role": "user", "content": image_content}
+
+        response = completion(
+            model=model,
+            messages=[image_message],
+            stream=False,
+        )
+
+        print(response)
+    except litellm.InternalServerError:
+        pass
+
+
 @pytest.mark.parametrize(
     "provider",
     ["azure", "azure_ai"],