bug#50853: python-feedparser

[Lio Novelli]

Feedparser module is missing sgmllib dependency:

    >>> import feedparser
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File
        
"/home/len/.guix-profile/lib/python3.8/site-packages/feedparser/__init__.py",
        line 28, in <module> from .api import parse File
        "/home/len/.guix-profile/lib/python3.8/site-packages/feedparser/api.py",
        line 36, in <module> from .html import _BaseHTMLProcessor File
        
"/home/len/.guix-profile/lib/python3.8/site-packages/feedparser/html.py",
        line 31, in <module> from .sgml import * File
        
"/home/len/.guix-profile/lib/python3.8/site-packages/feedparser/sgml.py",
        line 30, in <module> import sgmllib ModuleNotFoundError: No
           module named 'sgmllib'

From https://pypi.org/project/sgmllib3k/

https://github.com/conda-forge/sgmllib3k-feedstock

I'll try to provide the patch but this will be my first one and I'm
having some issues getting through (understanding) guix documentation
on submitting bugs and patches.