move back to pg 9.6 cause 10 is not working

SamSaffron · SamSaffron · commit 7e8ef5d6e11d · 2018-05-25T15:46:28.000+10:00
diff --git a/.travis.yml b/.travis.yml
@@ -17,7 +17,7 @@ env:
 
 addons:
   chrome: stable
-  postgresql: 10
+  postgresql: 9.6
   apt:
     packages:
     - gifsicle
