Merge pull request #174 from f5devcentral/fix-travis

Updating CI so focal distro images is used with python 2.7, 3.6, and 3.7

.travis.yml

@@ -1,5 +1,5 @@
 sudo: required
-dist: focal
+dist: bionic
 services:
 - docker
 env:
@@ -12,6 +12,8 @@ env:
 
 language: python
 python:
+  - "2.7"
+  - "3.6"
   - "3.7"
 
 before_install:
@@ -50,3 +52,4 @@ deploy:
       repo: f5devcentral/f5-sphinx-theme
       tags: true
       condition: $TRAVIS_TAG =~ ^v[0-9]+\.[0-9]+\.[0-9]*|^.*-stable$|master
+      python:  '3.7'