use latest generic-pool (brianc#1031)

Author: Tristan Davies

package.json

@@ -19,7 +19,7 @@
  "main": "./lib",
  "dependencies": {
  "buffer-writer": "1.0.1",
- "generic-pool": "2.1.1",
+ "generic-pool": "2.4.2",
  "packet-reader": "0.2.0",
  "pg-connection-string": "0.1.3",
  "pg-types": "1.*",