run tests on python3.8 (#2158)
run tests on python3.8 (#2158)


superdesk/superdesk-core,petrjasek/superdesk-core,superdesk/superdesk-core,superdesk/superdesk-core,petrjasek/superdesk-core,petrjasek/superdesk-core,superdesk/superdesk-core,petrjasek/superdesk-core