modify some errors and format some files by pycharm for nice-looking

[BUAADreamer]

Thanks for your great job🤗🤗! I have successfully run the code in the examples path with a little effort!!!

However, as there are some problems when I do experiments, I want to modify a little code for more user-friendly, so I created this PR. Modified contents are as follows:

1. modify replug Paper URL
2. modify bge default path in my_config.yaml and add bge query instruction for better performance
3. remove , in my_config.yaml, otherwise it will yield an error when running
4. format some files to make code read more easily (I hope you would format the whole project for reading or follow LLaMA-Factory to use make style&&make quality to automatically format code!)
5. move the from pyserini.search.lucene import LuceneSearcher to BM25Retriever to make running dense retriever more easily (as this requires jdk21, and it is somehow unnormal to use by Python projects, I think it is better to add to readme or requirements)

By the way, I think I can represent some of the users who use Pycharm, so this PR can also be considered an issue 🤗

I hope this project can get better and better, thank you for your efforts! 🤗

[ignorejjj]

Thanks for your contribution and valuable suggestions! I will take some time to format the overall code.