fix(package): update pg-promise to version 8.1.1 (#4602)

Closes #4587

Author: flovilmart

package.json

@@ -34,7 +34,7 @@
     "mongodb": "3.0.2",
     "multer": "1.3.0",
     "parse": "1.11.0",
-    "pg-promise": "7.5.4",
+    "pg-promise": "8.1.1",
     "redis": "2.8.0",
     "request": "2.83.0",
     "semver": "5.5.0",