Use trusty build environment

.travis.yml

@@ -1,4 +1,5 @@
 sudo: true
+dist: trusty
 language: c
 before_install:
 - openssl aes-256-cbc -K $encrypted_7d306b01dc1f_key -iv $encrypted_7d306b01dc1f_iv -in script/secrets.tar.enc -out script/secrets.tar -d