(maint) travis: test on ubuntu-bionic

Upgrade to bionic so that we can test pg-14. We install postgresql from
the official postgres repos, but xenial is too old.

Author: austb

.travis.yml

@@ -6,7 +6,7 @@
 # appropriate.
 language: generic
 
-dist: xenial
+dist: bionic
 
 # Always explicitly set sudo.  Otherwise travis' defaults may vary
 # based on when the repository testing was enabled.

ci/bin/prep-and-run-in

@@ -20,7 +20,7 @@ if [ "$host_type" = travis ] && [[ "$OSTYPE" != darwin* ]]; then
     # see https://github.com/pyenv/pyenv/issues/789 When using the
     # system python pyenv prepends /usr/bin to the path which breaks
     # anything that tries to override system defaults, like rvm/rbenv
-    pyenv global 3.7.1
+    pyenv global 3.7.6
 
     # Have to purge some of the existing pg bits so the 11 install
     # won't fail with errors like this: