Upgrade ubuntu version to fix CI:

Author: bogdan-dbx

.travis.yml

@@ -1,10 +1,12 @@
 sudo: required
 language: python
-dist: trusty
+dist: bionic
 matrix:
   include:
     # https://docs.python.org/devguide/#status-of-python-branches
     # One build pulls latest versions dynamically
+    - python: 3.8
+      env: CDH=cdh5 CDH_VERSION=5 PRESTO=RELEASE SQLALCHEMY=sqlalchemy>=1.3.0
     - python: 3.6
       env: CDH=cdh5 CDH_VERSION=5 PRESTO=RELEASE SQLALCHEMY=sqlalchemy>=1.3.0
     - python: 3.6