Fix API bug

There was a bug whereby for arxiv DOIs our API returned the full page and not the correct reference.

To fix this bug the only possible solution I found was changing the requested header and ask for an entire json dictionary with all the metadata regarding that specific doi. Then I added a function to extract just the fields that I wanted to display in the reference and concatenate them to create a string.

I tested my solution with all papers cited in notion/projects/qim_repository and it works, I also tested with some arxiv DOIs and it seems to work as well.