ci: try with the deprecated trusty

See https://blog.travis-ci.com/2017-12-12-new-trusty-images-q4-launch
5 years ago · 9cab16119a
1 changed files with 1 additions and 0 deletions
--- a/.travis.yml
+++ b/.travis.yml
@ -3,6 +3,7 @@ git:
  submodules: false
 sudo: required
 dist: trusty
+group: deprecated-2017Q4
 cache:
  timeout: 1200
  directories: