[FIX] cache: Wrap items into a list
[FIX] cache: Wrap items into a list

With 954825e1 the Request class expects that each URL parameter contains a list
to simplify the handling of it. With eedef173 the maintenance script itself
used the new `_params` variable but wasn't actually converting the entries into
lists so that the Request class thought (again due to 954825e1) the strings
itself were lists and thus joined each character.

Change-Id: Ie36a9adcb46675b576226d92e0b2c483b7e2f0d5

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