trying Python 3.9 and Postgres 12 in Travis

Author: dantownsend

.travis.yml

@@ -1,11 +1,13 @@
-dist: bionic
+dist: focal
 language: python
 python:
   - "3.7"
   - "3.8"
+  - "3.9"
 env:
-  - POSTGRESQL_VERSION=11.1
-  - POSTGRESQL_VERSION=10.6
+  - POSTGRESQL_VERSION=12
+  - POSTGRESQL_VERSION=11
+  - POSTGRESQL_VERSION=10
   - POSTGRESQL_VERSION=9.6
 before_install:
   - sudo service postgresql stop && sudo service postgresql start $POSTGRESQL_VERSION