Add node v16 to the test suite

Author: jeromew

.travis.yml

@@ -17,6 +17,11 @@ jobs:
         postgresql: '9.6'
       env:
         - PGVERSION=9.6 PGUSER=postgres PGDATABASE=postgres
+    - node_js: '16'
+      addons:
+        postgresql: '9.6'
+      env:
+        - PGVERSION=9.6 PGUSER=postgres PGDATABASE=postgres
     - node_js: '10'
       addons:
         postgresql: '11'