chore(package): update pg to version 8.2.1

Closes #39

Author: greenkeeper[bot]

package.json

@@ -29,7 +29,7 @@
     "npm-check": "^5.2.3",
     "nsp": "^2.6.1",
     "objection": "^0.8.0",
-    "pg": "^7.3.0",
+    "pg": "^8.2.1",
     "pg-escape": "^0.2.0",
     "sinon": "^4.0.0"
   },