epub parser not installed automagically

[wolfspyre]

if one adds an epub to the files list:

2024-03-18 22:14:05,813 - helpers - INFO - Upload Hugo_in_Action.epub saved to disk
2024-03-18 22:14:05,815 - llama_index - INFO - Service Context created successfully
Loading files:   0%|                                                                                                                                                                                   | 0/1 [00:00<?, ?file/s]
2024-03-18 22:14:05,816 - llama_index - ERROR - Error creating data index: Please install extra dependencies that are required for the EpubReader: `pip install EbookLib html2text`
2024-03-18 22:14:05,817 - llama_index - INFO - Document loading complete; removing local file(s)

Should that get automatically installed on filetype inclusion?
should it get installed as an initial dependency?
i don't really have a strong feel here... but the UI doesn't seem to be aware of, or present the error...

[jonfairbanks]

This should be fixed in PR #38.