Update .travis.yml

added testing for the rest of PG versions

Author: nad2000

.travis.yml

@@ -5,6 +5,9 @@ matrix:
     - env: PG_VERSION=10
     - env: PG_VERSION=11
     - env: PG_VERSION=12
+    - env: PG_VERSION=13
+    - env: PG_VERSION=14
+    - env: PG_VERSION=15
 
 services:
   - docker