Since the environment variable for pronto is changed
(https://github.com/mmozuras/pronto), it breaks current
travis CI check. Change it correspondingly.
Coverage remained the same at 98.799% when pulling da7b53b05e5f7966cd1546082ff23f9e3bea7b02 on fix_pronto_problem into b071a21936eb914655b35f9c4ccaa527621ec2ad on master.
Since the environment variable for pronto is changed (https://github.com/mmozuras/pronto), it breaks current travis CI check. Change it correspondingly.