feat: fix outdated get_expiration_dates function

[Icemap]

1. Updated get_expiration_dates function due to the Yahoo Finance page updated, which means the get_expiration_dates function is outdated, FYI: https://finance.yahoo.com/quote/IBM/options?p=IBM
2. Added unit test case for get_expiration_dates function to ensure the correctness.
3. Added lxml_html_clean in requires.txt according to the error message: lxml.html.clean module is now a separate project lxml_html_clean.
4. Updated Metadata-Version and Version.

[Icemap]

Before this PR merged, I forked this project and fixed a bunch of the functions in my repository. If you want to use the fixed package, you can also use pip install yahoo_fin_cheese to install or cover install the original yahoo_fin lib. And just use yahoo_fin_cheese like yahoo_fin, you don't need to change any code of it.

[amostech]

This PR should be merged! Thanks.

[amostech]

Also congrats for the fix on lxml_html_clean I also noticed that and struggled with the fix. I wish I had seen this PR before. :D