bpo-39035: travis: Update image to xenial (#17623)

Use image same to master to ease maintainance.
Remove "group: beta" to make Travis more stable.

diff --git a/.travis.yml b/.travis.yml
index 20912d5440be8ce807240bbbd69ed35eda061bda..aee8875de1639d8111fefb3e3924ffc5f68f6b15 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,5 @@
 language: c
-dist: trusty
-sudo: false
-group: beta
+dist: xenial
 
 # To cache doc-building dependencies.
 cache: pip