chore(package): update pg to version 7.16.1

Closes #60

Author: greenkeeper[bot]

package.json

@@ -58,7 +58,7 @@
     "mocha-performance": "0.1.1",
     "mysql2": "1.6.2",
     "nyc": "^12.0.1",
-    "pg": "7.6.1",
+    "pg": "7.16.1",
     "pg-hstore": "2.3.2",
     "plato": "1.7.0",
     "sqlite3": "4.0.4",