fix(test_prompt_manager)🐛: Ensure correct image content handling in t…

…ests

- Update the test to assert the correct base64 encoded image content.

tests/test_prompt_manager.py

@@ -243,4 +243,4 @@ def test_user_message_with_image_file(tmp_path):
 
     message = user(image_file)
     assert isinstance(message, ImageMessage)
-    assert message.content == image_file
+    assert message.content == "ZmFrZSBpbWFnZSBjb250ZW50"