fix travis pytest command
fix travis pytest command

ghamerly/problemtools,Kattis/problemtools,Kattis/problemtools,godmar/problemtools,Kattis/problemtools,ghamerly/problemtools,jsannemo/problemtools,godmar/problemtools,godmar/problemtools,Kattis/problemtools,jsannemo/problemtools,godmar/problemtools,jsannemo/problemtools,ghamerly/problemtools,jsannemo/problemtools,ghamerly/problemtools