[fix] enable 'monolingualtext' for WikibaseKnownTypesTests.test_datatypes
[fix] enable 'monolingualtext' for WikibaseKnownTypesTests.test_datatypes

- 'monolingualtext' is supported since 2c9b73630ad69455

Bug: T85385
Change-Id: I929e6e2c9e35e4b6198bbe138914a3c7263c546c

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