Bump min version of pg-pool

Author: brianc

package.json

@@ -22,7 +22,7 @@
     "buffer-writer": "2.0.0",
     "packet-reader": "0.3.1",
     "pg-connection-string": "0.1.3",
-    "pg-pool": "~2.0.3",
+    "pg-pool": "^2.0.4",
     "pg-types": "~1.12.1",
     "pgpass": "1.x",
     "semver": "4.3.2"