[bugfix] Re-enable TestCategoryFromWikibase tests
[bugfix] Re-enable TestCategoryFromWikibase tests

wikinews item for it was removed from Q6939656.
Use wikisource instead.

Bug: T192546
Change-Id: If84304780bbb2929b68d105801f6b46ab4b25953

wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core,wikimedia/pywikibot-core