[FIX] site_detect_tests: Don't test Gutenberg wiki
[FIX] site_detect_tests: Don't test Gutenberg wiki

The Gutenberg wiki returns 403 errors via Travis as their IP address is
blocked on the wiki. Thus the test won't reliably work.

Bug: T108671
Change-Id: I26141d6a73b594d798892a4ffd2552549b67b089

hasteur/g13bot_tools_new,hasteur/g13bot_tools_new,happy5214/pywikibot-core,wikimedia/pywikibot-core,smalyshev/pywikibot-core,trishnaguha/pywikibot-core,darthbhyrava/pywikibot-local,jayvdb/pywikibot-core,magul/pywikibot-core,TridevGuha/pywikibot-core,happy5214/pywikibot-core,PersianWikipedia/pywikibot-core,jayvdb/pywikibot-core,Darkdadaah/pywikibot-core,h4ck3rm1k3/pywikibot-core,icyflame/batman,npdoty/pywikibot,wikimedia/pywikibot-core,Darkdadaah/pywikibot-core,hasteur/g13bot_tools_new,VcamX/pywikibot-core,h4ck3rm1k3/pywikibot-core,npdoty/pywikibot,valhallasw/pywikibot-core,magul/pywikibot-core