bpo-36307: Travis: upgrade to Xenial environment (GH-12356)

CAM-Gerlach · methane · commit 74ae50e53e59 · 2019-03-18T19:44:58.000+09:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,5 @@
 language: c
-dist: trusty
-sudo: false
+dist: xenial
 group: beta
 
 # To cache doc-building dependencies and C compiler output.
