RSS feeds should only include items from approved feeds

[bmispelon]

As reported in #1299 (comment), the RSS feeds (that is to say, the actual XML files) for the feeds on the community page (blog posts, jobs, packages, ...) include items for feeds that are not approved.

When listing items on the site (for example https://www.djangoproject.com/community/packages/), such items will be correctly excluded.

The RSS feeds (in aggregator/feeds.py) should be modified to also exclude un-approved feeds (and some tests should be added as well).

[bmispelon]

@medmunds I've just deployed this change and the spam in the "new packages" feed should be gone now. Thanks again for pointing it out 👍🏻

[medmunds]

Much better. (I mean, still seven years out of date, but no more spam! 😄 )