Explicitly use policy=compat32

[hauntsaninja]

The documentation in https://packaging.python.org/en/latest/specifications/core-metadata/ claims that metadata should be parsed with compat32 policy.

The documentation in https://docs.python.org/3/library/email.parser.html#feedparser-api claims that policy should always be specified and that the default will change at some point. When CPython changes the default, that would presumably introduce a bug here.

[abravalheri]

@hauntsaninja, do you know if compat32 is compatible with UTF-8?

[hauntsaninja]

I'm not sure, although given that FeedParser takes a str, not bytes, I think it might have to do something weird to not handle UTF-8 (and from a glance at the CPython code I'm not seeing anything weird).

Note that this PR doesn't change the policy, it just makes it explicit (as recommended by the Python documentation, due to future change of default).

[hauntsaninja]

@takluyver added the mention of compat32 to the core metadata spec docs I linked (in https://github.com/pypa/packaging.python.org/commit/3c855a61bc095fab8d75daabc5a00be38f60b2df ), so would probably be best placed to answer questions about it

[pradyunsg]

Thanks @hauntsaninja! ^>^