Update Travis CI to use Ubuntu 18.04 instead of 16.04

diff --git a/.travis.yml b/.travis.yml
index 297a19cdcdb42dc3cf0f3bf5a4d00737609870f9..660749f3298eaa4b617feaaf4860d08138032153 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,5 @@
 language: c
-dist: xenial
+dist: bionic
 compiler:
   - clang
   - gcc